[MrMagic]

At some point, all videos started to display only a black screen with sound and I had to restart the Shield to get it working again. Sometimes it just helps to switch DV off and back on again on the Shield.

You do not need to restart the shield, if you don't get the right colors anymore. For me its enough to change the advanced display settings (don't know the exact Englisch name) to something without dv and back to dv again. Let me know if this also works for you.

Yes this works for me, as I already wrote in my message above

@sk83 I tried your Matrix build with advanced settings. I didn't play around with the timings yet, but I think the behavior is about the same for all builds: sometimes it works and sometimes it doesn't.

To fix it, it helps to turn off Dolby Vision and then back on again in the Shield's display settings. I suppose this triggers some kind of reset of the video engine. Like @hoppel118 said, maybe there is a way to execute that reset in software somehow?