Windows is a bit stupid and doesn't understand removable media with multiple partitions. Write this 'image' to the card and it will overwrite the MBR partition table; erasing knowledge of the partitions. Windows will then see the SD card as a normal unformatted drive again:
NB: The LE USB/SD creator app has this "image" listed under the Tools download section.
Known issue with currently no known fix: https://github.com/LibreELEC/LibreELEC.tv/issues/7166
Kodi uses the "Videos" menu to give a quick file-browser interface. It does not show any artwork unless the file happens to have been scraped into a library view (and thus references to the artwork-to-use are available). The "Movies" and "TV Shows" menus are library based, you need to "scrape" content in to them; either using internet scrapers or a local file scraper (which would e.g. find local artwork in the same folder). I suggest you have a read of https://kodi.wiki/view/Scrapers.
Not that I'm aware of, but the better place to ask would be the Kodi forums (under add-on development). NB: Profiles is one of the icky areas of the Kodi codebase; lots of old code that is known to have issues and nobody really volunteering to maintain it.
If you're primarily going to use LE, perhaps make a little effort to understand Games in Kodi.
I don't understand Passthrough Audio.. why do we need to enable it at all?
Some/Many users (esp. those with ATMOS and HD-capable audio setups) obsess over quality and pass-through will ensure Kodi processing does not "degrade" their audio experience. In practice multi-channel PCM output is close-enough to pass-through in quality that the silent majority of users probabaly can't tell the difference (or don't care enough about the difference). I personally can hear the difference, but use PCM output 99% of the time simply because it allows volume control to be done from a single remote control; enabling pass-through requires me to dig up the AVR remote instead. I do enable PT occasionally for special films, but that's not often.
You need to share the system journal log showing boot and deletion of something, then the same log showing the reboot/next-boot.
In the ARM SoC world most devices have CEC support built into the HDMI hardware on the board. In the x86(64) world it's rare so regardless of HDMI or DP connection there is probably no CEC support and you'll need to add an IR receiver device. My personal recommendation would be the flirc USB receiver as it's stupidly simple to setup and works with any IR remote you have, but it's not the cheapest and there are plenty of USB IR devices on eBay etc. that can receive commands from an 'MCE' remote or similar.
HDR support in Kodi is still a little WIP but I'd start investigation with the current 'Generic' nightly as this will have newer kernel and drivers and that may (or may not) help with recent-ish Intel hardware.
if (sector_size != 512 &&
sector_size != 1024 &&
sector_size != 2048 &&
sector_size != 4096) {
sd_printk(KERN_NOTICE, sdkp, "Unsupported sector size %d.\n",
sector_size); ^ the error message in kernel code (drivers/scsi/sd.c) suggests the 256kb size is the issue so I'd suggest reformatting the drive to use at least 512kb or perhaps 1024kb and then restest to see what happens?
Some early support for basic things like pin-ctrl and clocks are being submitted to the upstream kernel. However, the kernel maintainers require things to be done to a much higher standard than Amlogic engineers are used to, so each patchset requires many iterations and progress is proving rather slow. Ask me again in six months.
It's best to ask for help in the add-on support thread in the Kodi forums (most add-ons have one). It's not really a LibreELEC issue.
And what is the default sector size? .. I don't use Windows.
Kodi documentation on emulators is similarly lacking. I've installed https://github.com/zach-morris/plugin.program.iagl and when I select e.g. a SNES ROM Kodi will ask which emulator to use for playback, and if not selecting one that's already present it will install one from the LE add-on repo and then things just play. There is no "Library" for games but I save regular ROMs as favourites and access them direct from there. I also have IAGL configured to cache ROM files to avoid repeat downloads and give faster starts. Other distros like Lakka, RetroPi, Batocera will be more poilished for gameplay and less polished for media. LE is more optimised for media, but the game stuff does work.
RPi4 does not support VP9 hardware decode but it has enough CPU grunt to software decode the limited amount of 1080p VP9 content that I have for testing. It just runs a bit warm(er) over time so needs a decent passive-cooling case. Hardware decoded H264 (to 1080p) and HEVC (to 4K) playback is excellent.
Odroid C4 should similarly support everything software decoded up to 1080p; upstream Linux support for everything except the media bits is solid and quite mature now. You might need to disable hardware decoding completely to solve the H264 issue; the current H264 support in the upstream kernel uses the VDEC driver for GXBB/GXL/GXM boards. Newer G12A/B and SM1 boards need to use the newer (and badly named) HEVC driver that supports H264, HEVC and VP9 codecs and there's an issue with 10-bit/4K media. After a multi-year wait someone is currently known to be working on a sponsored rewrite of the HEVC driver .. although I didn't see code to test yet.
Kodi has a local filesystem scraper. You still need to define sources, content type, and scrape; to populate a library view.
The only way to ensure something 100% boots from SD is to erase eMMC (preventing eMMC boot) or to use the special HDMI dongles that force different BL1 (silicon bootrom) boot priority. However, for reflash of eMMC you only need to ensure that the kernel is running from SD card. The initial u-boot stage from eMMC and then discovery and boot of kernel and userspace files on SD is fine since the binaries that run are on the SD card. If you attempt to flash eMMC when booted from eMMC it will start and the lock-up when you overwrite the apps that you are using to perform the flash.