I have AppleTV 4K connected to Sony XE9005 TV via HDMI 2 port (HDR enabled).
The TV is flashing in white periodically (like each 3 minutes or so). AppleTV automatically chooses 4K HDR and it picks Chroma 4:2:0
The HDMI cable is the one that Apple sells in the stores from Belkin.
Any ideas what is going on? Or just crossing fingers and hoping that a new update is going to fix it?