I've recently upgraded from a 1080p Samsung to a 4k Panasonic, and now I'm having an issue where the screen is blank/black after turning the TV off then on again. If i turn the TV off then turn it on again quickly Kodi is displayed as expected, but if I leave a 5-10 minute gap (or longer) between turning off and then on nothing is displayed. The only way to get Kodi back is to reboot the HTPC.
Screen is a Panasonic TH-55GX850Z, and LibreELEC (9.2.3) is installed on a ASRock J4105-ITX.
So far I've tried a new HDMI cable, and setting a Custom EDID (per the instructions in the wiki).