Really just shooting in the dark here. I cant tell scale/ value without a ref point.
You say you have 2 sensors. I see the other sensor is showing close to the same value at the cursor time line. As a trend, are they both reading the same values? If so, I guess my bad sensor theory is out the window.
Are your sensor outputs calibrated correctly to your logger?
Many WB controllers have configurable outputs. I usually set the low voltage(rich) to .5 volts 10:1 a/f ratio. Then set my high voltage(lean) to 4.5 volts 20:1 a/f ratio.
This gives wiggle room when setting the logger/ecu input values.
There are very few instances when I see NO offset voltage between output and input readings on two separate devices.
I check the offset amount by setting the wideband controller to send out a straight line voltage, regardless of a/f ratio.
As an example...
10:1 a/f = .5 volts
20:1 a/f = .5 volts
Now your wideband should be outputting .5 volts no matter what the ratio is. Check your datalog. If the voltage doesn't read .5 volts, you need to mathematically change either the output voltage, or the read value.
Do the same with the high voltage...
10:1 a/f = 4.5 volts
20:1 a/f = 4.5 volts
Same deal. I keep that .5 volt window on the high and low side for offset changes. If you don't need the "windows" on the high or low side, you can widen the voltage swings(.2 volts-4.8 volts) to get better resolution.
The reason I asked about sensor ground commonality, is there are frequently these ground offsets. Some manufaturers dont want other devices to share, and some do.