I’m pretty sure this is related to the problem I would occassionally have:
For me it’s hard to trace to a specific action and it doesn’t happen on all projects. Could be after render in place, or bounce or applying offline processing on an audio part.
The result is exactly as you describe - meters show audio playing, outputs are set up correctly in Cubase, audio interface is setup properly but there’s nothing going through to any of my audio interface’s outputs, EXCEPT - click is still working. Never seen this happen on Cubase 12.
Coincidentally, my interface is RME too. Mine is Fireface UCX, what’s yours? I tried reinstalling RME drivers, but it still happens.