I have had similar issues with the thunderbolt/ ethernet adapter and a retina MBP. Solution for me was a restart with everything connected before restart. Something with accidentally disconnecting thunderbolt while plugged in and having to replug it, cat didn't like it.
I know USB ports are a scarce resource on a MBP but I have had good success with USB3 adapters as well, they don't seem to come unplugged quite as easily.