If anyone has seen/is seeing this, there is an open and unconfirmed issue in the GNOME project bugzilla database[1]. It's reproducible for me but that's not enough to confirm it.
I built the required ports with debugging and was able to extract traces in gdb for this. If you run into this and want to add this to your built ports, you can add the requisite bits to your Portfile(s) as well.
so far a solution is elusive ;-)