Playback on Shield Chromecast not working anymore


Today I figured out that playback on my nVidia Shield TV (2015 Pro) doesn’t work anymore (Roon Core on a NUC with ROCK). Both Core and Shield are on my ethernet network.
Chromecast session seems to start but only a grey screen is displayed. Roon logo doesn’t appear and I have to go back to home screen or wait till it fails (transport error displayed on Roon Remote)

I tried multiple times, restarted both Shield and Roon Core but still the same.

I tried Chromecast with the Youtube app and it works perfectly.

The only noticeable change is the upgrade of the latest Shield Experience 7.2, but it worked right after the update.

Have you any idea of what to do next to find the source of the problem ?

I noticed this problem this morning… and I tried again this evening…

Now it works again. I have no clue of what happened.