On the MBA was the adapter at least showing up in Network Preferences?
That is my next diagnostic step.
When I plug the adapter into the thunderbolt port, a new item should show up in Network Preferences, right?
On the MBP it did not show up...because the adapter was plugged into a display port, not a thunderbolt port. -- NOTHING justifies terrorism. We don't negotiate with terrorists. Those that support terrorists are terrorists.