Hi,
Thanks for all the work on the testbuild. I have only been testing it for a few days as I just got an HDR tv.
Up to now it's all smooth and HDR playback works great.
The issue I have is when stopping HDR playback the GUI is stuck in HDR mode. Playing SDR content keeps it in HDR mode. Only option I found was rebooting Libreelec and then it shows the GUI in SDR.
Display settings are in 1920x1080p, GUI resolution limit is set to 1080.
This doesn't happen all the time but 9 out of 10 times it's stuck.