It didn’t used to do this behavior, but something changed several server versions ago. I didn’t make any changes to this album before, why is this not working right anymore?
That looks more like it’s duplicating the tracks from one disc, rather than mixing the tracks from both. Is this the only album where this has happened? My multi-disc albums aren’t doing this under the same Plex build, so something must have gone wrong.
After a couple of months of not working right, I updated the server to the latest version 1.21.0.3608, this problem has stopped. I did manually refresh metadata for these problem albums (ones with more than one disk), problem resolved without me changing any metadata.
Yet another problem in the world resolved without comment or explanation.