User blog comment:Godisme/Zirconis' Magic/@comment-2214433-20130510183802/@comment-7418318-20130510184501

Maybe we just overlooked Mavis because she is so tiny :P

On a more serious note she probably kept some distance from the large crowds. It might cause problems if someone who can't see her were to bump into her. In the OVA she was holding a glass and bottle, so she does seem to have a physical body, albeit it's invisible to most people.