Picture 1: Right rear caliper outboard pad is not notably contacting and wiping the rotor "clean". Post wash water and general light rust building up and not getting cleared. It can be felt on top of the rotor surface with a finger. Picture 2: is the left rear and operating properly.

I first bled and it didn't solve the issue. This included bleeding the opposite side.

I then rebuilt the caliper and it's still happening. I again re-bled both sides for good measure.

It was mentioned in a FB forum I may have pad contamination, so today I swapped outboard pads side to side. Upon doing so, I noticed the right rear (problem side) slid right out; whereas, the left rear had to be forcefully removed. The right rear (problem side) inner had to be forcefully removed as well, so it tells me the inner is working just fine. The outboard side piston is extended from the rebuild fully pushed in position and touching the pad back but it seems there's a lack of pressure to force it against the rotor. I haven't drive it yet as it's not at my residence so I haven't tested the contamination theory; however, being the problem side pad was loose compared to the other 2 I pulled, I don't have confidence that's the problem.

The only thing I haven't done is to unplug the Electronic Brake Actuator; however, I've never done that when doing brake fluid bleeds in the past and never had an issue. Never seen anyone doing it on forums etc. in the past 10 years of ownership neither.

Pads and rotors have less than 10k miles on them.
Brake fluid is less than a year old, Castrol SFR.
Brakes lines to the caliper are braided stainless steel and not binding etc., OE right height.
Car has 103k miles on it, no leaks in the system and it's used as a street car only.