Why would my TM not populate while working, after I confirm segments?

Yesterday towards the end of a 19,000 word project in a 17 MB sdlxliff file prepared by a regular client, Studio began crashing (2019 SR1). In itself, tiresome, but not too much of a problem as Autosave works and I was in the home stretch so I just kept working. 
However, around the 95% mark, the file stopped opening at all. The error message is "The file at location []correct location] does not exist!
Again, tiresome, but it should have been easy enough to create a new project and populate that using my TM. But no. My confirmed segments are not showing up. Nothing. I'm back where I started.
Why? What setting is different that means my TM is not updating when I confirm a segment?