YES!!! I Solved it.
After doing a factory reset on my TV it started to work.
Then, when I did all my general settings on the TV it stopped working.
So I decided to do all settings step by step and it turns out that when I set my TV's "ENEGERY SAVING" to HIGH (because I don't want it too bright in my bedroom) then it disables the IR on my RPi.
Probably because it's gaining noise on HDMI? I don't know.
Anyway, I'm glad I solved this. Thanks for all reactions.
BiTRiP
I already disabled CEC on TV and in LibreELEC under Settings/System/Input devices/Periphials/CEC.
It's not possible to totally disable CEC on a RPi.
I tried on both 5V and 3.3V. but no luck with on this TV.
The powersupply is bought together with the RPi and is a 2A adapter.
Can try another one but I doubt if that will work. I'll let you know 
Could be this: RPi2 OSMC Logitech Harmony One Issues With GPIO IR Sensor
No, because my gpio IR is just working fine when I hook my monitor onto it.
It's just not working when my TV is connected to it.
Ok, got a little further but it also got stranger.
It turns out that my Samsung TV is disabling this IR somehow, even when I disable AnyNet (CEC) on TV.
When I plug my RPi on my pc monitor (also samsung) with the same HDMI cable the IR is just working fine!!
I disabled CEC in Pheriphials settings in Kodi, disabled Anynet on TV but it ain't just work with this TV.
What has that to do with the GPIO IR? Except from CEC. 
Thanks,
BiTRiP
I also have two Asrock ION 330 boxes and never had ANY problem with sound. It's just working out of the box with fresh install of OE or LE. No any config needed.
So better check your cable or tv source. (I had once with a appletv that a hdmi port on a tv was also for dvi and got no sound. Changing to other hdmi port gave sound)
Does the box give sound if you startup with a linux livecd like ubuntu? Just to test sound.
Don't the component strips on your breadboard go across the short way?
Ah yes, that was pretty lame. It's the first time I use a breadboard. Thanks 
Unfortunally it's still not working when putting it the short way.
LibreELEC:~ # dmesg | grep lirc
[ 4.713545] lirc_dev: IR Remote Control driver registered, major 244
[ 4.762167] lirc_rpi: module is from the staging directory, the quality is unknown, you have been warned.
[ 5.653958] lirc_rpi: auto-detected active high receiver on GPIO pin 18
[ 5.654135] lirc_rpi lirc_rpi: lirc_dev: driver lirc_rpi registered at minor = 0
[ 5.654140] lirc_rpi: driver registered!
[ 5.896071] input: lircd as /devices/virtual/input/input0Strange, I just can't get it working.
I have new IR sensors now and I'm fully sure this is remote is working fine. (it still works on my asrock).
I re-imaged the SD Card with a clean LibreElec 7.0.2 and only put device_tree_overlay=lirc-rpi in end of config.txt.
Boots up but remote ain't working, neither irw is picking up something.
Any ideas?
What type of IR receiver are you using now?
I don't know the exact type of the sensor. It was recognized as Tenx Technologies Inc.
As far as I know It was using the Nuvoton MCE driver in the past when it was built-in the Asrock.
Hopefully receive my order tomorrow so I can test with the TSOP4838.
Thanks xbmcnut,
My IR sensor is fine. I just put it back in Astock HTPC and still working.
But I also ordered a TSOP4838 sensor so will try tommorrow with that one too.
It's not working for me either.
LE seems to reconize the receiver perfectly by only adding in device_tree_overlay=lirc-rpi in config.txt.
But it's not receiving any signal by irw using a standard MCE remote from my Asrock HT330 (asrock_ion330ht_blu_ray_4.jpg)
Using LE 7.0.2 on RPI 3.
Any help?