...been trying to stay out of this thread but here goes.
I've had basically the same problem twice in the last 3 years and both times it was the PAD. (to thick)
When I retired I delivered parts for Advance Auto Parts for several years and, as most of you can guess, on more than one occasion, I picked up pads for return that were boxed wrong, labeled wrong and even mixed pads in the same box. Whew, there, that's my story.
...I've enjoyed reading some very good answers/thoughts though!
Not much else I can add to what's been said.