ipod touch playlist - albums go out of sequence

ipod touch 6th gen, iOS 10.3.1, itunes 12.6

I guess this would also apply to an iphone. Since I updated to 12.6 the sequence of playlists created on the ipod changes. No matter what order you add an album in, the playlist changes the order the albums are stacked in. The tracks themselves stay in the right order, but if you add album A then album B, chances are that the playlist will line them up B then A. There doesn't seem to be a strict logic to it - you can often overcome it by adding two albums in reverse order, but add 3 albums and that doesn't work.

This was an initial problem with 12.5, I think, and it got fixed quite soon, but now it's gone back to its bad old ways. Don't Apple do regression testing?

I can build playlists on itunes and import them to the ipod, but can't reliably create them on the device itself