Possibly related: A few weeks ago I was told to use the autosave option of MS word. The login dialog went through, but then nothing happened. Classic Microsoft. I reinstalled Onedrive, autosave said it's on and I go ahead with my work. That was friday 3PM. Come monday, I find that the last 2 hours of friday are gone and spend about half an hour looking for it. I Ctrl+S about every 5 seconds so I can't imagine that there's no copy of it anywhere. But there wasn't one, it was just gone.
What happened was that onedrive was stuck trying to upload my VMs (I had those in my _local_ documents folder, which onedrive claimed ownership of during reinstallation without telling me). Onedrive never showed my excel file in the list of files it was uploading, so it could have either tried to do the VMs first and never got to the excel file or quietly errored out on that without ever uploading it.
In any case, I'm still dealing with the fallout of the fatal mistake I made: Trusting a microsoft product to do the absolute fucking basics.
Maybe I'll learn this time.