0. Prepare a filter a, b, c
1. Dropdown the filter and select a only In the filter dialog and OK.
2. Should see a appear only.
3. Dropdown the filter and you should see only a is checked and option (Select All) is semi-checked (a small squire)
4. Uncheck the option a, and you should see the option (Select All) is unchecked, too.
5. If not, it is a bug