I have a very similar issue. I have 3 secondary sites. Two of them are other offices that connects to us through our MPLS network. We can image from those offices just fine. The other office (the one with the problem) connects to us through a VPN tunnel. I feel like that may have somethign to do with it. Also, when creating bootable media, I am only ever able to select the MP of the primary site. Should the scondary site MP's be listed there? I am running R2.
Hopefully someone has found a fix to this problem.
smsts.log