Display settings of roles do not save

(updated, restarted)

The display settings of roles do not save anymore. (They did some days ago.) Specific example are the toggle buttons if members should be grouped according to roles, and if it should be allowed to address the role with at symbol. 

The alert that there is an unsaved change pops up, but when I click safe, the message disappears and all toggles switch back to the previous setting.