Unable to modify resources

When I edit an existing resource (I change only it’s name) and then save it, after the “weak password” notification is closed, the “edit resource” window will stay there forever with an rotating circle on the “save” button. I can only get rid of it when I reload the page, and then the change has not been saved.
I can create new resources and I am able to edit those. The issue is only with existing resources.

Last changes on my installation: update to v5.1.0, created metadata key, use shared metadata key.