New easy workaround for current Xbox One issue for those on preview program - High Contrast Mode
So today I was doing some of the quests in the insider hub app. One of them is to trial the new high contrast modes. There are light and dark high contrast modes in the current alpha and beta insider build. On trying the dark mode I thought it looked pretty cool for a change so kept it.
An hour or so later I realised it wasn't all it was cracked up to be. OneGuide looks awful and it was clear that the mode isn't optimise for use in most apps. However before changing it back I decided to watch a bit of TV. It was two hours before I realised that every episode I'd watched had not had the issue.
I thought at first Plex might have pushed an update but when that turned out to not be the case I narrowed it down to the high contrast mode. On switching back and forth between high contrast mode and normal I've been able to confirm that high contrast mode in both light or dark resolves the issue of the overlay remaining at the start of media being played.
TLDR: High Contrast mode looks like crap but fixes the issue.
Hopefully this helps some people - at least until the issue is fixed.