I'm just installing civicrm for the first time under drupal 9. On my very similar test system on my home pc I can add new items to the menus such as defining membership types. But on my real system it only works for the very first definition. For the second I can add text to the Name field but on clicking the mouse no other fields are accessible and even the Name field is frozen. So the only to do is cancel.There are no messages in the log. I see the same problem when adding entries to contribute/payment methods. It seems to happen when there is already some entries in there. I looked to see if there was a way to import/export configuration as a workaround but that doesn't seem to be available.