I have experienced this a few times in last few days: Editing a previously almost acceptable Location to move the observation eg 10-20 metres away, either in Bulk Edit or as a single observation, results in the Observation showing the wanted co-ords but the pin moving hundreds of miles away, and the Obs thus no longer appearing in any Collection Project.
eg https://inaturalist.nz/observations/27309923
using coordinates copied from other observations that have the GPS I want, eg this one:
https://inaturalist.nz/observations/27309920
I have tried several decimal points and Accuracy values. The accuracy of 7m works for another obs with these co-ordinates.