This is a cosmetic user notification issue in Users List.

This will probably rare as a community gets populated with Users but I am reporting this anyways.

If there are no users with photos, then nothing appears on the screen after clicking the left sidebar - Users with Photos
If there are no Online users, then nothing appears on the screen after clicking the left sidebar - Online Users

Some type of notice text would be good.

Screencast: http://screencast.com/t/htIxO5mXAtJk