I will repeat my message from the other thread here, since the HDMI bug with the high bandwidth settings is still not fixed unfortunately :(
The HDMI bug happens every one or two days or so.
If you have a HDMI port (I use HDMI 2) set to one of the high bandwidth options (Optimal, Optimal Auto Game or Optimal Auto Game 120 Hz Pro), the TV somehow “forgets” this setting. I notice this for example by my Nvidia Shield 2019 Pro no longer showing Dolby Viosn, or my PC no longer able to use 4K 120 Hz. I have HDMI 2 connected to a Denon X2800H receiver.
To fix the issue, you need to go to the HDMI Ultra HD option of the HDMI port in the TV setting menu. It will still show the correct setting, but you need to switch to another setting and then back again to get the high bandwidth back. After that, my Shield immediately is able to show Dolby Vision again.