https://sourceforge.net/apps/trac/sourceforge/ticket/20001
I wanted to add "Topics :: Multimedia :: Graphics" to my job listings. However, it complains that I left a field blank. That isn't possible. There are no fields that can be left blank. This was for the Image Upload Provider project (imageuploadmgr).
Confirmed, trying to add "Topics :: Multimedia :: Graphics" to a Help Wanted post results in an error. Seems to be an issue specific to that item though; I tried a couple other random skills and they all worked fine.