Paul,
I have tried to replicate your sticky Nitro result by doing the following,
I had already started to give the car here a quick once over with HD Speed and had no real intention of doing a true correction before reading your post, so the end result won’t be the same.
However it was 30c outside so our temps are close and I moved the car so part of it was exposed to the sun; I also applied Nitro via DA. (I find it quicker and easier I also use a little more doing it this way.)
I found that the Part A went on the whole car fine, when applying Part B I had no problem on the section that was in the shade, but I did find the pad bite a little on the section that was in the sun.
Removal was not a problem for either section.
I would suggest that the surface temp may have been just that little too high especially being black paint????
The first time I applied Nitro I found it a little harder to apply and remove, although I believe I was trying to put it on to thin. The next time I used it I used the DA and a little more product and haven’t had a problem since.
Hope it helps
Daniel