Stuck on "Loading the map"

OK
You have a javascript conflict beaking the rest of the page.
It shows on the Tooltip script but it might coem from other extension, like chat. Can you test disabling it ?

Your backend error is because the map has been created by User 42 and the user doesn't exist anymore.
There is nothing broken because of that, but if you want to get rid off the error , you can edit the database table to change that user id by an existing admin user id.

That was it: we deactivated the Freichat and the map is working again.
The strange thing is that we had installed a free version of Freichat and there was no problem with Geommunity. We installed a purchased version on Saturday, so that's when the issue must have come up. Will contact the programmers of Freichat. Thanks for your time!