I have a 6core, D500, Mac Pro late 2013 with 64GB of RAM, and a MacBook Pro 15" late 2013 16GB of RAM and 1TB SSD (nVidia 750m). I used a Thunderbolt Bridge connection which had to be manually finessed to accept a two way green light connect. I've set everything up in Compressor to allow a render on both computers and for five minutes or so I do get both giving a "Busy" report during a render. Then one drops to idle, then it's not available, then it vanishes. I manually added the Mac Pro and the MacBook Pro using the IP address of each and though this reconnected the missing computer it would not last. I discovered a tendency for the Thunderbolt connect to drop the manually selected port that when applied. This was the only way to Green Light & allow both computers see one another but not always in Compressor. I would be thrilled if it is my actions that have caused this but have read on Apple's forums that there are others with an issue.