BuddyDocs bug with Groups

Yeah, me again. This one’s more serious, I think. BuddyDocs is confusing me; the way it connects with Groups is hard to fathom, but without Docs enabled for Groups, it seems impossible to share Docs.

Using up-to-date WP and BP.

In the back end, I can go to “associated items”, and check boxes to associate an existing Document with groups. My site has two groups. I’ve enabled Docs for both groups in setup. I discovered that if I check both boxes, I generate errors in the Doc: eg,

Warning: Illegal offset type in wp-includes/cache.php on line 674

appears when I go to look at the Doc, and then a succession of other errors ennumerated where the Doc’s text should be if I open it.

I ran a few tests, and clearly it’s only checking both boxes on a Doc that causes these problems. But I can check two boxes. So the back end is signaling to me that a Doc can have multiple group associations (whether via editing an existing Doc or clicking “Add New”); meanwhile, the front end only allows a Doc to be associated with one group.

Which is correct? Is this a functionality problem, or a problem with the back end fooling me into thinking I have functionality that doesn’t exist?