kbfs: files mysteriously stopped uploading

_(I also asked this in keybasefriends kbfs chat.)_

problem: files are no longer uploading (this is a copy to a mounted kbfs, not git)
question: How can I troubleshoot why it simply stopped uploading?
system: Fedora 32 server (no GUI). Been using Keybase on this system for years, updating consistently.
version: keybase-5.6.1.20210125164223.f3b21527b9-1.x86_64
situation:
- under `DirtyPaths`, a directory and two files beneath it are listed (i.e., as found in `/keybase/public/toddwarner/.kbfs_status`)
- `kbfs fs uploads` says nothing is in process
- `kbfs fs stat [filepath]` gives me the file info and `NOT_STARTED`
- there are no conflicts listed in any of the `.kbfs_status` file that I can see
- quota: I have used kbfs for years and years now, but my quota usage is relatively small
- devices: I have two devices with kbfs mounted, but I only write to the fs on one device
I waited a long time today for kbfs to sort itself out. It is unchanged after a couple hours.

my log id: 509cffa4aaea798c9a34451c

Start with the reported .kbfs_status entries, `kbfs fs uploads`, and `kbfs fs stat [filepath]`, then correlate them with log ID 509cffa4aaea798c9a34451c. Done means identifying why the files remain `NOT_STARTED` and documenting or implementing a verified resolution; the issue names no source file or test.

Written by the indexing model from the issue text.