virtualmin GPL create/delete/edit user hangs

Hello,

Operating system CentOS Linux 7.2.1511 Webmin version 1.821 Virtualmin version 5.04 Theme version Authentic Theme 18.20

Deployed domains with users a while back.

Now I wish to add additional users to a domain. The create/delete/edit domain user web forms time out on the operation.

I tried with virtualmin theme and the operations also hang. Provisioning new domains continue to work. Managing other services with virtualmin continue to work.

Any advice on how to fix the issue?