Stubborn o2 Sensor issue - downstream, CEL, P0157, bank 2 sensor 2

Hi All,
I had my cats stolen. Then had them replaced--at a muffler shop--not Toyota. Toyota, at the time, had a three month wait for OEM cats.

After several trips back to the muffler shop, bank 1 sensor 2 is all good and no trouble codes.
Bank 2, sensor 2 continues to trigger P0157.
I've had four different sensors and same result.
I just picked up the fourth sensor today at Toyota and same result.
I'm reading live data with an Ancel OBD2 reader which has been helpful.
Temperature at catalyst bank 2 sensor 2 is same as catalyst bank 1, sensor 2.

Oxygen sensor voltage is same between b1-s1 and b2-s1.
oxygen sensor voltage output at b1-s2 is in range between 0.1 and 1V.
oxygen sensor voltage output at b2-s2 starts off low and then in less than 1 miles goes to zero.
I can see it raising a P0157 code in less than two miles.
If I drive enough miles--50-60 miles, it throws CEL and of course notes P0157 code.

I've even swapped sensors from one side to the other and I get the same result. B2-S2 low voltage.

The muffler guy has been over both sides of the exhaust and I even had it inspected by another shop that said the welding and cat work is tight and good quality.
the same cats are on both sides---so no differences there --and bank 1 is checking out fine/not throwing any codes with over 250 miles.

I've looked at the connectors and the wiring and I see no obvious damage, but I have not pulled stuff apart and dug deep into that.

Another shop mentioned that IF it were the ECM or computer, it would flag immediately and it wouldn't wait for the 50-60 miles to throw the CEL. He said to focus on the sensor. I'm on my fourth sensor (last one OEM/Toyota). Other sensors were Bosch, Denso, and another Denso.

I appreciate helpful feedback. Thanks!!

 

Any updates on this? I am having the same issue and at my wits end lol