Adding saml provider to groups not working


when I try to add my saml providers to any of my ldap groups I receive this “The LDAP object could not be saved: Der Wert darf nicht verändert werden. Attribut=mailAddress alter Wert=None neuer Wert=”
but I can add them to users directly. What can I do? (Univention 5, latest updates)

Best regards

still not working, kindly asking for help