What are the values from the 4 gas test?
I think the scanner is not correct. Most scanners have a function to give information from the lambda sensor in text, this value changes constantly from rich to lean. I think you see these values but the scanner puts them onder the open/closed loop function.
When the engine is running fine, lambda is correct en fuel trims are normal, then you might have a cat problem.
Normally this should give a dtc, but sometimes there is a 'dummy' placed for the second lambda.