@ivan - this fix didn’t work for me at first and I have a question.
When I installed build 1676, I went to 
> Displays and saw that the ROCK/NUC HDMI output connected to my Denon AVR was currently Disabled:
Yet the TV connected to the AVR was showing the Roon screen:
Which raises the question: shouldn’t this show the diagnostics screen when the Display is disabled?
So I then Enabled the Display, attached it to the Denon Zone and started the display:
No change on the TV - it still showed the Roon screen and I was playing something on the Denon Zone…
I tried another Zone with the Display and the same thing - just Roon displaying.
So then I restarted the Roon Server using the Web Administration Interface (not a full Reboot of the NUC) and now Zones are being correctly displayed.
So it would seem that after installing 1676 an extra restart of the Roon Server is necessary?
However, if I disable the Display - the TV still displays the Roon logo - how do I see the diagnostics screen or has this now been removed?