In our case, all our administrators must respond to all triggers. However, not all people are allowed to edit all hosts in all hostgroups. So in the actual configuration, we have some hosts where the users are not allowed to use "severity change" or "close problem". But there are some triggers where this is necessary or desired.

With tag-based permissions, only the triggers that correspond to the filter are displayed when the tag filter is activated, even if in another assigned group for the corresponding host group has complete read permissions without tag filter are assigned.

Current behavior:
Group 1: Read permissions on Hostgroup "Servers"
Group 2: Read-Write permissions on hostgroup "Servers", tag filter on "tag1".
User is member of both groups.
Result: Users only see the triggers with tag "tag1" and have all rights on them.

Desired behavior:
Group 1: Read permissions on Hostgroup "Servers".
Group 2: Read-Write permissions on hostgroup "Servers", tag filter on "tag1".
User is member of both groups.
Result: Users see all triggers of the host and can ack them and have Close/Severity-Change rights on the triggers with tag "tag1".