1- There is no speed 5.5 on the PC

2- I too am surprised that the white pad left any marring... was the pad and car thoroughly cleaned?
3- You could be working the product in for too long. I'm quite confused why people work in finishing polishes and AIOs for so long... they usually break down right away...
4- You could try a lighter pad or try the white again with a different technique: crank the speed up to 6, use little to no pressure and move the PC a little faster than you normally would. That should do the trick. Good luck.