20.19 ride corrupted on save

I've almost never seen this kind of failure on any Edge device, but I got it today. Finished my ride, saved it, saw that it saved, but it wouldn't sync over wifi. Plugged it into computer, and I saw that the fit file which it had saved was only 10k. (!) Weirdly, the overall stats did somehow make it to Garmin Connect, but the absence of the 'charts' tab is the clue that most of the data is missing.

More worrisome than losing this morning's ride is the potential to lose all the data for much longer events.