I went to a similar issue. I ended to start from scratch with the upgrade process. Fortunately I left my production system alone and did the upgrade on a separate PC, just to figure out how it works and if it is save...
I am in the middle of the second try, Well - not really in the 'middle' as my import of the rekordbox 5 library is at 10% progress.... :-( (22500 tracks)
Would be the 3rd night in a row this PC doesn't shut down because of the migration....
This definitely need improvements...
