Audio files in multitrack go offline after saving

I have a multitrack that consists of a single audio mp3. It's just been cut and rearranged.

When I save the sesx, all clips suddenly go offline. I can select all and relink (the folder that opens is the folder where the original is) and continue working just fine. But as soon as I save again, the clip goes offline and has to be re-linked.

The audio file is an mp3, but I don't think that has anything to do with it. Both the audio file and the sesx are on different mapped network drives. Again, not sure why that would matter in this case. Just not sure what is going on.

Operating on the latest, Build 13.0.7.38