I don't have much classical, but I had a few albums of various genres that wouldn't play in order too. No matter what I did, there was always a random track that was first in sort lists. After a little while, I somehow stumbled onto this -
Highlight the entire album, right click on get album info, and make sure it is album 1 of 1, 2 of 2, etc. Sometimes this info was missing on a track, and it put that track first.
For multiple disc albums, rather them one at a time, I change them so it's 1 of 1, then renumber the tracks of the following discs. By doing this, Pink Floyd's The Wall plays all the way through rather than having to start disc 2's tracks after disc 1's end.
Highlight the entire album, right click on get album info, and make sure it is album 1 of 1, 2 of 2, etc. Sometimes this info was missing on a track, and it put that track first.
For multiple disc albums, rather them one at a time, I change them so it's 1 of 1, then renumber the tracks of the following discs. By doing this, Pink Floyd's The Wall plays all the way through rather than having to start disc 2's tracks after disc 1's end.