so LibreELEC USB-SD Creator, Etcher and win32diskimg is failing to flash a usb drive
So if for a lot of people working and only for you not... it's logic to be something with the program and not at your side....
nothing is wrong with my usb ports, has to be some thing to do with permissions
Did you tried to run the LibreElec USB-Creator with admin rights (right click to icon... "Run as administrator")?
I had a suspiciously small number of wifi networks detected.
The problem disappeared as soon as I changed hdmi port on my TV. Initially I was using the (e)ARC port.
Hi, the RPi's built in tiny wifi antenna is notoriously weak. Maybe it's some kind of the EM field of the HDMI cable what could make interferences. What you can try it, change the HDMI cable with one with better quality and EM shilding, and if you have a USB-Wifi dongle, you should try it too, usually works far better than the built in.
I can dual boot with Windows 11 and that works fine sharing.
The old and repetitive story of the NTFS support under Linux (and LE)... Or something like that. 
I had something like this with my dual boot (Win11 & Xubuntu) PC. In your case probably that's happen because in the Windows 11 is set active the "hibernation flag" (or something like this).
Search (google it) for how you can disable the hibernate/suspend/fast boot options in the Win11 and you sould be fine...
Where should I begin?
Check the Wifi first. Possible you have a weak connection and not enough for the video files with higher bitrate.Try it with a USB-wifi adapter (one with a "real" antenna). Better if it's possible to switch to cable connection. I recommand to avoid the onboard wifi on the RPi with that tiny antenna (this is when the size it's matter 
).
It's not so easy to boot linux from USB, with UEFI bios these days.
Isn't too complicated at all. I'm using a USB stick with "ventoy" installed as boot manager and a lot of bootable ISO's on the stick. Only the "ventoy" needs to be installed on the stick, after that you can just to copy almost any bootable ISO files to the stick (live linux and even Windows installer ISO too). In the case of UEFI bios, just once need to enroll the key from stick, more info here: https://ventoy.net/en/doc_secure.html
You can always install EXT4 driver on Windows laptop.
True, an EXT4 driver for Windows coud be the simplest way in that case.
Hi, I don't know if this will help you... I had issues with special characters in video subtitle files. The solution was to change the "Character set" in the "settings - player - subtitles". Maybe you should try to search in the settings for "Character set", probaly exist somewhere one for handling the info files too. 
As for expectations for NTFS support, I was using Linux with NTFS drives on an old laptop for many, many years and never had such problem. I never saw this coming.
I'm using too something like this, a dual boot (Win11 & Xubuntu) PC, and I had issues with the NTFS partitions, become better after I disabled hiberantion option in Windows. And yes, for the partition what I want to be "simple" and always usable in the both, I'm using exFAT. Mostly this linux-NTFS issues coming after a "dirty disconnect", like sudden disconnect/power down, what couldn't be expected in the case of the HDD assembled in a laptop.
Not sure what an issue means for you, but it is without a doubt an issue for me, as my current setup is not usable, due to the HDD randomly just dissapearing from LE with no reason, no that I can think of.
To simplify more this, I think the NTFS issue isn't LE related. It's in the linux kernel. So I think the right place for this could be somewhere in a linux development forum, kernel section. And about if it could be "resolved" soon or not... just try to think from another side, to report an issue in a Windows forum as you have difficulties with reading EXT4 linux partitions and you don't have full suport for it...
You have concern about EXT4 and how to read it if your RPi with LE become defective. You have 10TB data on an external HDD, did you think ever, enough a little bigger mechanical shock and that disk could became defective, without chance to recover any data from it? I learned before, from my own bad luck and defectiv HDD, to don't keep important data in a single location.
Sorry, but exists issues without a simple (or at all) solution and this probably is one of them.
Seem like this is a known issue.
Is questionable, if it's an issue or not. Like Chewitt explained above, it's more about the different OS handling a disk with active error flag. And as the NTFS is Microsoft proprietary, developed for Windows OS, I didn't think to have ever a "perfect" support under linux for it.
For removable drives the best compatible way is the exFAT partition. A bit less good in error handling, but better support in all OS's. There's a lot of comparition between exFat and NTFS (and EXT4), just use the "google" if you want to know more. I'm using a "big" USB stick for storing media files (RPi4B, LE12), formatted to EXFAT, and (till now) didn't had any issue.
I need this drive to be also compatible with windows in case my RPi / LE fails.
"IF" your RPi will die (RPi's never dies 
), you can boot your PC from a USB stick and live-linux (any kind of Ubuntu) and save your data from the EXT4 formatted disk. That's isn't a real problem. If you have linux (LE) and want stability use a linux partition.
This problem was not occuring when I was still using Odroid C2 with the same HDD and older version of LE, so maybe there's something there.
Nobody said isn't exist support for NTFS at all under linux. Just not guaranteed. Sometimes it's weak, sometimes enough (or it looks like enough for you).
I've never used that kind of RF antenna splitter, I only used others like this one, but usually it has a signal quality loss
Something like that it could be enoug, no need to be exactly the same.
Because it's a passive splitter, always exist a signal loss. Something splitted in two, always result two halfs. The question is, that "half" will be enough for a tuner or not.
Usually a good antenna could povide enough signal for two tuners, you should check it. If not, you could try to use a short antenna cable as possibile, or/and an RF amplifier. The beter could be to use an antenna with built in amplifier.
I'll consider using a bigger microSD card to save recordings, I hadn't thought about this option.
That option have advantage and disadvantage at the same time. I prefere to keep my media file on a separate drive (USB stick in my case). That could be a major advantage when needs to reinstall the whole system (somethings went wrong, major system upgrade). So I recommend to think it twice to keep your media/personal files in the same drive (microSD) as the LE system. Maybe if you have a "not too slow" USB stick, you could try it for TV recordings. If you will go with TVheadend, it's a bit of work to set it in webinterface, but after that it's very stable (at least my experience).
Another thing, I'm using at an RPi3B+ with 3 USB tuners (as TVheadend server, just watching, without recording) for years without any serious issue. I think the streaming from tuner isn't need too much RAM, probably for recording is the same.
How did you inter-connected Xbox tuners?
Did you mean about antenna connection? Use a simple RF antenna splitter, something like this:
Entering Libraries such as Movies and Shows is quick. Entering a plain SMB folder is dog slow.
Hi, sure it's a SMB issue? If I understand correctly, when you enter into Movies or Shows is quick, for another folder is too slow. Maybe the LE 12 it's scanning that folder when entering into it, or trying to update the library... and this to lead to that delay?
Still haven't found time to update but I have another question: I want to do the update with tar files put in the .update folder, do I have to use some 10 version of LE first and then 11 or 12 so as everything works ok and I don't have to do a clean install? Thanks
Why you don't take a backup, copy it to a safe place, and try it? Upgading from LE 9.2.6 to 12 it's a very big jump and you still didn't specified your hardware, so maybe the real question is, what it's more time costly? Trying the upgrade and resoving the issues that sure will be, or a fresh install with all the new setup and addons and docker containers...
Between the LE 9 and LE 10 were big changes, and at that time the upgrade wasn't recommended. At that time I tried the upgrade from LE9 on my PRi3B+, I spent a lot of time to resolve all the issues, and finally I deleted everything and made a fresh install. But maybe on another hardware could work (or not... 
).
2. How do I get automatic connection to wifi at boot?
go to Settings > LibreELEC > Connections > YourNetwork > edit connection and search there for autoconnect option.
Did you test le13? Im still looking for a solution
I tried... installed on a spare sd-card, start to make the settings, added few addons (TVheadend client, Audio-profiles, Aeon Nox skin) and got some strange things (bugs?), so I abandoned, maybe didn't ready for daily use yet (or I didn't had enough patience )...
Hope this gets fixed soon, its very annoying.
Looks like isn't fixed till now. I have 3 RPi (1x RPi3B+ lan, 1x RPi3B wifi, 1x RPI4B lan) connected to my router, all with fixed IP. Yesterday I tried some settings in my router and after each router reboot, all the RPi with LE12 lost the connection and needs to be restarted. All devices using latest LE12 nightly... Somebody tried if the LE13 nightly have the same network bug (I will try in the next days, just to have time)?
so I still need to get browser access to TVheadend
I'm using the TVheadend for years without issues. Probably you should start again from begining. Delete all TVheadend (sever & client) stuff, reinstall only the server and try to connect to the web interface (http://libreelecIP:9981/). At the first time access should start with basic/user settings autoamtically.
Also, it asks me the password from time to time on both 2.4 and 5Ghz SSIDS, even when I haven't changed it at all. I entered the actual one, and it rejects it! It's crazy. Then it appears and connects itself.
I had something similar with one of my RPi (the only one without cable), became it far better after switching off the "zeroconf" (settings/services/general) and applied an auto reboot cron job for every night. Try it too if you want.
But that is true, something could be wrong with the wifi connection in LE ("iwd[393]: event: connect-failed, status: 16"), I have devices using the same wifi (phones, tablet, laptop), none of them had any same (re)connection issue (waiting for the password, but doesn't accept).
I keep my previous opinion, if you have any possibility to switch to cable, do it! Far better connection, no more password-encryption, stable speed...
