I've been posting Documents in a Secret group, Chicago Section Private Business (as admins I suppose you should be able to see it and its contents). My project: upload all the components of our Section Manual and have various responsible parties edit them with the ACS Network's fabulous collaborative editing tools.
Each of these documents contains the tag "chicago_section_manual". After creating a number of them, I created a Category named "Section Manual" within the group, and associate it with that tag. Bueno, I look in that category and see all my components there.
Then I decide to edit one of those components by changing its title. I do so, and LO! it's no longer in the category. On inspection of each of the other Documents, I find that if you click "Edit", and check to see it the Document is in that Category, then the box isn't checked. If I check it, it gets added back to the Category.
Weird, eh? Seen it before? Known bug?
Workaround is trivial, but I thought you'd like to know this weird problem exists.