2005 Altima Reversed O2 Sensor Signals

So I've got a weird one here. A customer brought in his 2005 Altima 2.5 to get the cat replaced. He provided the part, so I went ahead and replaced it. I had previously diagnosed it as a bad cat, given various other things that pointed to it being a problem (and cat debris in the exhaust upon removal). I test drive the car after finishing, and I took a look at the O2 sensor data to make sure everything looked good. It did, with one problem... the sensor readings are reversed.
B1S1 is showing a steady voltage of around 0.4v, and B1S2 is showing a oscillating voltage as you'd expect to see from B1S1. Now unless Nissan has some weird glitch with this or a different way of classifying O2 sensor locations, this is completely backwards.
I unplugged the upstream sensor to confirm, and sure enough, that sent B1S2 to reference voltage (0.05ish).

My first thought when seeing this is that the sensors could be reversed, but that's literally impossible on this particular car. Has anybody run into this? I've been searching around, and I haven't found anything on this sort of issue on a 2.5 Altima.

I figured maybe it was just the scan tool/OBD or manufacturer mode difference, but the lean fuel trims point to this being a problem. Whatever is going on here probably killed the cat in the first place.

I'll attach a screenshot of the O2 signals.
 

Wire diagram shows an A/F sensor B1S1. A six wire plug.
B2S2 A four wire plug.
You can also check the hood emissions sticker.
It should show (1) AFRs (1)HO2S.

That's what I'm seeing on the diagram as well. Maybe the data looks weird because of that. I honestly don't know where it's getting that voltage reading, if it's in fact an AFR sensor.
I'm going to check further today. I realized as well that when I disconnected the upstream sensor, the codes that it threw were in fact for B1S1, even though the live data showed B1S2 to go dormant.

How were those readings taken?
Lab Scope, OBD generic , Or Nissan .
I have found sometimes OBD Generic will Take an A/F reading , Make it a 0.- 1.0 volt reading.
Are the fuel trims good?

They were taken on OBD2 generic. I looked on the manufacturer specific software today, and the readings looked to show B1S2 as the upstream, however there was also an AFR sensor reading.
STFTs look great, but LTFT sits around 9.5%. For now, all monitors are ready to pass emissions inspection, but I still think the LTFT is way too high. If I recall, this was an issue before, and there were no vacuum leaks or anything of that sort.
The plastic around the AFR sensor connector is broken anyway, so I'll probably recommend new sensors simply for that reason, along with their age. Although they appear to be responding. The upstream sensor hangs around 1.4-1.5v, and when I hit the gas quickly it shoots rich (2.5-3v) then settles.

Thats not too bad 9.5 LTFT . It may improve at cruse.
1.5 v A/F would be a bit rich. I would not worry much . Looking for perfection on a 2005 is asking a lot. MHO.

Gotcha, I wasn't sure how Nissan sensors read rich/lean. Every manufacturer seems to be different with that.

Thanks for some reassurance on this one! The customer has the same mindset, he's a younger kid and just wants the car to get him around. I told him to get the car inspected right away, then if the CEL popped back on then we'll worry about it then. After test driving, the only thing I found notable was that high LTFT, but like I said, the monitors were all golden so I guess it's fine.