External Wideband Help

I have the MPVI Pro and am using a datalogging output from my wideband, the sensor is a Bosch LSU4.9 AFR (8.5-18)
While datalogging my AFR randomly drops down to the 7:1 range, but the gauge is reading normal (like 13:1 or 11:1) it seems to only do it as the engine runs rich
Is something wrong with my math? Anyone else using this sensor that can share their formula?
Ive scoured the forums and have only found one post sharing the math for setting up the external input.
I am having some electrical gremlins, but should the gauge and datalog be consistent?