T-case Calibration Issue

[rootehound]

I'm at a loss...
I have a 2005 2.5 with around 255,000 miles on it. A few years ago, the front drive shaft started making some noise. I took it to a friend who has a lift in his garage. (My friend is a brilliant semi-retired mechanic with tons of BMW experience. I've been bringing my cars to him since the 1980s, without any problems.) When we took it out to replace it, we noticed the front bearing in the t-case wasn't looking good and decided to rebuild the t-case, even though it wasn't throwing any codes. I ordered all the parts from Cobra in Florida. The parts came and we rebuilt the case. After re-installing it, we could not get it to calibrate. (Using my friend's Autel.) Figuring that we might have installed something wrong, we took it out and apart again. This time, we videoed the rebuild and sent the video to Cobra. The owner ( a very helpful guy, with a ton of experience with these t-cases) said everything looked good. BUT, once again we could not get it to calibrate. I then ordered a new (Bosch) actuator motor, but that didn't change anything. I ordered a used transfer case module. We coded it, but it made no difference. Since the car is my backup / beater car, which I don't drive often, I just figured I'd live with it being 2 wheel wheel drive.

This is where is gets strange. I also have a 2010 with around 150,000 miles on it. A few months ago I started hearing a t-case noise. We decided to rebuild this one despite our last experience. Again, I ordered the parts from Cobra. Using the video from the first rebuild, we put it together and installed it. Using the same Autel, it calibrated and has been working perfectly.

What the hell?

Does anyone have any idea why one car calibrated with no problem and the other won't calibrate at all? I can live with the beater being 2 wheel drive, but it would be nice if it was AWD again.