Users have ACL access to just a couple of groups, one of which is a smart group and a subset of the other. Although they can see all the contacts that they should, when going to 'Search' and select 'Groups' they get 'None found' which makes no sense. In other, different installs but at the same level (5.28.3) users can see and search the groups their ACL permits them to, but cannot see other groups. One clue is that these users were removing people from groups (in error) so,a few weeks ago, using the 'Contact Summary Layout' I removed the 'Groups' tab from the summary page that they viewed. So I restored this but that didn't fix the problem. In trying to diagnose the problem I looked at a different group of users with ACLs and can see the same problem there, so something seems to have happened to this install - yet it's been on 5.28.3 almost since that was released. I've hit a wall with this - can anyone help?