Had the same problem as everyone here. I live about 2.5 hours away from the closest Apple store so repair time isn't a quick thing for me. I took my TB display into the "genius" bar, they kept it for a week while they replaced the tb/power cable on the display itself. They tested it there, said it worked fine, I plugged it into my laptop and of course, battery was full so couldn't "really" test. Got it home, ran the battery down some and of course, it will not charge connected to the TB display.
Plugged in an older MBP (I have a MPBr) power cable, took the adapter off the display power cable and of course, it did not work either.
Called Apple AGAIN, explained AGAIN what was going on, told them about my testing...it's obvious to me that it's the adapter. I think I got a "new" technician...he was fairly clueless.
Long story semi short, they are sending me a new adapter, of course after they place the hold on the credit card until I send the original one back. I hope this works.