Import Domain: No hosts available in data center (RHEV 3.2)

Our RHEV 3.2 installation has 5 data centers (4 local storage, 1 NFS v3).  The NFS DC has 12 hosts, and the other 4 local storage DCs have one host each - In the Import Domain window, there is a 6th (!) data center called "(none)".  All 16 hosts are visible, but only in the "Use Host" menu of the "(none)" DC.

This can't be right.  Anyone know whats going on?