Another Sort Order Question

I have a lot of compilation albums (not CDs, ones I've made up myself). They used to be in folders in alpha order (Artist - Title) but when I added then to LMS I added a track number at the front of the filename. There may have been a reason for that but it's lost in the mists of time. But it makes adding to the compilation a chore since new tracks don't always work best at the end of the list. So I tried deleting the track number part of the filename and removing the Track No tag. The problem now is that the tracks within each folder are sorted (by LMS) by title, rather than by artist, and I can't for the life of me work out how to get them sorted by Artist - Title, which is how they appear in the folders.

On the Interface tab in Server Settings I have Title Format set to Artist - Title but I can't find any other settings that might affect the sort order.

By the way, all tracks are tagged fairly simply and there are no 'sort' tags. Also these tracks are all tagged as compilation tracks.

Any help appreciated.