That is what happens when one of the pistons stick. Bite the bullet, new callipers and rotors along with pads is the right decision. Watch your hoses to make sure of no bulge. But usually the dust shield on a piston brakes open and allows contamination past wrecking the piston to bore area.

 

Ugh I already did that last fall

 

Since U have replaced the likely culprits and still had the return problem it is a residual PSI problem most likely for that wheel. Go back upstream slowly. But the return problem, the stuck piston and worn pad + damaged rotor won't go away without replacement if they are damaged again. Most of all I would inspect that caliper very closely. It is not impossible to get a bad one off the shelf. Coincidences SUX. It isn't unheard of to have pads not wear in. I order matching pads and rotors together usually. Possibly the seals were damaged on installation accidentally? Brake parts!