If I customize the "Refresh" function to be the key combination that I would press to type a question mark, the shortcut displays as "Shift +/". When I press Shift+/ with an active Contact Sheet, it refreshes (for example, if I am in the "selected" filter and select 3 images on the contact sheet, it refreshes to only show those 3 images). When I press the / key on its own, no refresh occurs (but the Contact Sheet does rescan and if new images were added to the directories it is displaying they do appear).
At this point, it would probably most effective if you gave us a phone call and we did a screenshare so I can better understand the issue, as I am unable to reproduce the issue on my test machine.