UMap - Changes keep reverting

I use Umap to map out tribal areas. I’ve been working on one for quite a while now, and now the changes I make to the map keep reverting. I definitely had this happen multiple times, even though I clearly save while having a good connection.

2 days ago, if I made changes and saved, the changes would revert instantly, but upon reloading they would reappear. I worked more on the map yesterday, but then in the evening, the changes reverted again.

Strangely, any changes in names/text in any of the objects do remain.

Can anyone help?

A few weeks ago in uMap: Logout nach Bearbeitung (German) similar problems were reported.

On which server do you work (.fr/.de/other)?