[ovirt-users]oVirt 4.5.4-1.el8 - unable to add users

Hi, I have oVirt 4.5.4-1.el8, deleted expired user, and now unable to add any user / group. Typing user name, press “Go”, and the nothing happens. Restarted oVirt engine VM, no changes. How to fix this problem? Thanks in advance for any help. Andrei