FOLLOWUP -- this only happens across NFS, which means I have to reproduce my music repo on my local box.

OS: NetBSD pre-10
Collection: NFS mounted mostly FLAC, some .mp3
Problems: SQLite3 fails to import some song records from the flac labels, keeps trying, and keeps failing:

01:41:12.342 ERROR Database:502                     Unable to execute SQL query:  QSqlError("19", "Unable to fetch row", "NOT NULL constraint failed: songs.ctime")
01:41:12.342 ERROR Database:503                     Failed query:  "INSERT INTO songs (title, album, artist, albumartist, track, disc, year, originalyear, genre, compilation, composer, performer, grouping, comment, lyrics, artist_id, album_id, song_id, beginning, length, bitrate, samplerate, bitdepth, source, directory_id, url, filetype, filesize, mtime, ctime, unavailable, fingerprint, playcount, skipcount, lastplayed, lastseen, compilation_detected, compilation_on, compilation_off, compilation_effective, art_automatic, art_manual, effective_albumartist, effective_originalyear, cue_path, rating) VALUES (Eat for Two, Blind Man's Zoo, 10,000 Maniacs, Blind Man's Zooartist, 1, 1, 1989, -1, , 0, , , , , , 10,000 Maniacs_id, Blind Man's Zoo_id, , 0, 212133000000, 919, 44100, 24, 2, 1, file:///mnt/music/+ALPHA_ARTIST/10,000_Maniacs/1989.Blind_Mans_Zoo/101.Eat_for_Two.flac, 2, 24388448, 1605390365, , 0, , 0, 0, -1, 1640079642, 0_detected, 0_on, 0_off, 0_effective, , , 10,000 Maniacs, 1989, , -1)"
01:41:12.342 WARN  ScopedTransaction:37             Rolling back transaction

...and I end up with an empty collection, and no songs in my DB after exiting strawberry.
Why would it end up with an occasional null ctime?