Question About 'Tag - Filename' Action

I have a large folder of classical music that is tagged and organized horribly. I like my tags to be simple: Artist - TrackName.
A number of the songs are tagged as follows: 05 - Georges Bizet - Prelude (Carmen).mp3
When I use the 'Tag - Filename' option (%artist% - %title%), it appears as: Georges Bizet - Prelude (Carmen).mp3
This is exactly what I want.

However, I'm noticing a pattern. On tracks where the TrackName comes before the Artist, for example: 04. Miserere mei, Deus - Gregorio Allegri.mp3
When I use the 'Tag - Filename' option, it renames the file '-.mp3', instead of 'Artist - TrackName'.

Maybe it's not a pattern, I get the same thing on the following track as well: 008. Antonín Dvořák - New World Symphony (Op. 95) - Largo.mp3

Any help would be greatly appreciated.

Be sure that you recognize the difference between a 'tag' and a filename. The 'tag' or the 'tagging' is the internally stored metadata consisting of multiple 'fields'. The standard fields are typically TITLE (what you may be calling trackname), ALBUM, ARTIST, TRACK (track number), YEAR and GENRE. It sounds as though you may be a little confused about this and think that the tagging and the ARTIST and TITLE (%artist% and %title%) are contained in the filename.

In the cases where you end up with '-.mp3', the ARTIST and TITLE fields in the tag are most likely missing. The pattern you've observed is probably just a coincidence.

Yeah, I finally looked into the documentation AFTER posting this thread (shame on me). On the plus, I now know what I'm doing. On the downside, my classical collection was tagged in so many wildy various ways I pretty much had to do everything manually.