Can't modify ABM server settings

Can't modify ABM server settings

Hello, 
Desktop Central version 10.0.611 UEM Edition
Suddenly, ABM server settings won't open when choosing "Modify Settings". 
Tried to restart the server, didn't help.
Screenshot attached.

What will happen to already synced/enrolled/pending devices if I delete the ABM server and add it again? Will they be removed from Desktop Central MDM as well?

                  New to ADSelfService Plus?