Thanks! Then you ran into the issue from the thread I picked up on you:
We ware actually working on that and will provide a fix.
For the moment I recommend to NOT use Cubase nor Nuendo 14.0.20 MediaBay Window for tagging. Tagging from HALion, Groove Agent, or earlier versions of Cubase / Nuendo should be fine and the new tags will be available in the global MediaBay (Server).