Transmission failure

[GLBLWARMR]

My truck is now in the shop going on its third day. The dealer is having to work with GM on the mainland to try and figure out the problem. I am curious if any of you have run into the following issue and if you have what was the cause.

Over the last week after driving for about an hour or so the tranny would get loud and start to whine. There were no grinding noises at anytime. The tranny heated up to about 200 degrees and at that point it cut out/disengaged or at least that what it seemed. The truck was still running and was in gear but it was almost like it shifted into neutral. I would shift through the gears but it did not make a difference. The engine would revv but the truck would not move. I shut the truck down for a couple of minutes to let it cool off and it would work fine until it heated up again. I called the dealer and they got it in the shop right away.

Is there a sensor or something that would disengage the transmission to prevent further damage once a certain temperature is reached? The service department is dumbfounded by this and have never seen this before. At no point did any service lights come on. The truck only has 17k on it.

If anyone has any insight into this I would love to hear it. Thanks