I have the same problem in WebUI that specific local groups doesn’t list their members. In my opinion it’s a problem with spaces/blanks in (local) group names. All my groups with one or more spaces/blanks in name are not list their members; all others do. The problem can also reproduce at command line:
For example there is a group with groupname it test an 2 members.
sudo -u www-data php occ group:list-members it test - return an error
sudo -u www-data php occ group:list-members “it test” - return the 2 group-member
With groupname in apostrophe the result is ok. Can I change the relevant command for WebUI request?
There is an another entry in this forum to a similar issue: Groups show number but not show list
With regards,
Lars