This problem is related to https://forum.inaturalist.org/t/observations-failed-to-add-to-habitats-s-afr-project-in-web-uploader/8682 insofar as I caused it while trying to improve obs field upload for @karoopixie: we were uploading a lot of unnecessary data, so my theory was that something there may have been related to her issues uploading lots of stuff over a relatively slow connection. However, while I thought my solution was submitting only the necessary data, it was actually submitting no data at all.
Sorry about that.
I have a fix queued up and hope to release it this afternoon… when I will no doubt introduce even more problems.