String Settings UI: Multiple edits loses data on Save

Testing #77427 I can put multiple settings into edit mode. When pressing "Enter" to commit an entry, the data from the other settings is lost. Probably should only allow for editing of one setting at a time. Repro: * search for `validProper` settings to show the three `Valid Properties` settings:  * Click "Add Item" on each one, add a value to each:  * With focus in the 3rd item, press "Enter" to commit the edit. Result is that edit is committed, but the data from the others is lost:  Suggest that you can only edit one setting at a time.