Eventually, this issue closed for me. I changed my HD.
I had my collection on 2 locations:
- A networked NAS
- An external USB-connected HD. Roon would go on and on adding and identifying.
Then I added an M.2 internal HD. I copied all data from the external USB drive over (took a few hours only).
- I disabled the external USB HD location in Roon
- I added the new M.2 HD as a location in Roon.
- Roon then proceeded to add all 46K tracks in a few days.
- Today it finished and Roon now performs perfectly.
Hope this helps those still struggling.
Gert