I just picked up a new Raspberry Pi 3B+ from Amazon to mess with 3D Blu-Ray .iso playback and it'll only work with LibreElec 10, 11 & 12. If I try 9, 8 or 7, the green light on the Pi long blinks 4 times, then short blinks 7 times. This is apparently a power issue, but I can confirm this is definitely working perfectly with 12.2.1.
I tried different MicroSD's and I also tried extracting the .iso and using different software to image the MicroSD, but it's always the same result. Is this a known issue, or did I just get a defective Pi?
Edit: I just confirmed it also works with v10 & 11. Supposedly 9 is required for 3D Blu-ray playback though, so I'm still trying to figure out what's going on...