I see the same problem with Mac OS 10.8.5, Multibridge Pro 9.7.7 and After CC 2014.
The latest driver available from BM for our Multibridge is 9.7.7!
This problem is with AE CC 2014. Premier CC 2014 is fine with the 9.7.7 drivers.
I checked another workstation that has Decklink 2 with BM 9.9.3 it didn’t work as well.
I then updated on that workstation the BM driver to 10.1.1 and it works!