The problem is now fixed, a vertical scrollbar is displayed as neccessary.
SongKong uses existing metadata to match songs and to validate acoustid matches, but sometimes existing metadata should not be used. The most common culprit is track names of the form Track 1, Track 2, Track 3 ectera , whilst these can be valid track names they normally are not so now if existing metadata contains such names we just treat as if the song currently has no title.
This regression was introduced in SongKong 3.9 by the change to match multi-folders groupings to Discogs after a failed MusicBrainz match before attempting matching sub folders. Unfortunately this change could cause Discogs matching to stop prematurely, it is now fixed in this new release.
Full list of fixes and improvements can be found here