Group's 'Faces' tab missing members

I manage the Western Montana group (thanks to whomever for finally approving us, by the way!) The group's block shows we have 7 members, but the Faces page shows only 4 members. The list tab seems to correctly show all the members.

I use OG on a pretty large SocNet site, but I've never seen this before. Any idea what's up?

Thanks for all the hard work the g.d.o. team puts in to give us a great home here!