I recently changed my core from an iMac to a Mac Mini, and all the albums that I had added from Qobuz and Tidal disappeared from my library, the playlits that I had created in Roon also disappeared. Is there any way to recover my music?
If those albums are in your ‘Favorites’ on the T/Q sites, then they should re-populate without any actions on your part, including any Restore. Still, try a sync from within Settings==>Services.
Any playlists you created in Roon will need to be Restored from a Backup.