Don't remove album number

Please show us your file naming script (see Options > File naming). It needs to set the %tracknumber% in the script.

If you use the default the issue likely is happening when you just save your local files and those don’t have an album artist set. Please see the following answer on you to fix the script:

Are you actually tagging your files against MusicBrainz metadata (by looking up your files on MusicBrainz and saving the results on the right pane) or are you just manually updating and saving your tags in the left pane? If you don’t know what I mean take a look at the Quick start guide