Administrator unable to see other Virtual Servers

We have a server running Webmin 1.741 on Ubuntu Linux 16.04.2 with Kernel Linux 4.4.0-127-generic on x86_64 with 2 Administrator users where one of the users unable to see any Virtual Servers except their own.

Configuration:

• 8 Virtual Servers total
• Affected user has all module permissions in webmin.acl
• Affected user has home directory as /, browse unix files as 'root'
• Both users are members of sudo
• No password expiry configured for affected user, I had it configured for mine however looked to be breaking Webmin/Unix password sync so disabled it

Have performed following:

• Restarted Webmin
• Reset password using changepass.pl
• Matched Webmin and Unix password
• Had user clear cookies

I have fixed it previously by creating a new user with permissions that worked then renaming the user however as it's come back again I'd like to understand the root cause, suspect it's related to Webmin <> Unix user, if someone can explain how this works would be appreciated.