i'd put money on the pad being stuck where it's supposed to slide before saying the pots weren't working properly

you should be able to spot the problem by getting someone to press the brakes pedal while the wheel is off so that you can see whre the problem is occouring

i can also rememebr soemthing about some calipers wearing one pad out before the other because of it being leading and trailing, but i always thought that was only the case with drum brakes