Shells listed in user manager are limited to showing what is in /etc/shells and will not show /sbin/nologin
The /sbin/nologin option is not available and is not the default since updates from upstream in Oct 2018. Systems with the Shell Extension app installed since then are affected. Systems which contained the file prior to this should have taken the update as an /etc/shells.rpmnew and use the previous file. Systems installed with fresh 7.6 will be affected.
Admins should review their user list and validate by running:
Add the /sbin/nologin to the /etc/shells file. Reset the login on each user affected.
An additional workaround is to manually adjust the shell used in LDAP with a manual LDAP edit using ldapmodify or ldapvi.