Marking up a pdf on an iPad: markups randomly disappear

I'm assuming this is yet another bug that Apple refuses to fix, but here goes:

1. I save a pdf from my macbook. It's linked to iCloud, so
2. I open the file on my iPad (from Files).
3. I work on the file, marking it up.
4. Every once in a while, all of my edits for the last N minutes will disappear (where 0 < N < 10, typically).

It's as if the file is sync'ing with iCloud, but pulling the wrong way, if that makes any sense.

Anyway, it's super frustrating as it costs me a lot of time here and there.

All OSes and apps are most up-to-date releases.