psyapathy Sorry, no time to actually debug that. You can however try to build your own image and your own addon. Use following repository:
GitHub - jernejsk/LibreELEC.tv: Just enough OS for KODI
Command to build OrangePi Win image:
PROJECT=Allwinner ARCH=arm DEVICE=A64 UBOOT_SYSTEM=orangepi_win make image
Command to build addon:
PROJECT=Allwinner ARCH=arm DEVICE=A64 scripts/create_addon <addon name>
andreabak OpenELEC image used kernel which doesn't consider EDID at all. This was one of the pain points. You had to change fex file if your monitor didn't support 1080p. Besides, only 1080p, 720p and few other patched-in resolutions were supported. Here, on mainline kernel, a lot of stuff is based on EDID. Can you post output of following command?
edid-decode /sys/class/drm/card0-HDMI-A-1/edid
There are some other possible differences. AFAIK, mainline HDMI driver doesn't set correctly metadata like colorimetry, aspect ratio, etc. This might also be the problem.