[BUG] (Smart Filament Sensor false positive)

[JaVelin-X]

Smart filament sensor triggers filament runout signal after 40 seconds printing time. resumes as expected if you press resume but errors out again

I have updated to the latest 4-28 2021 firmware from BTT for the TFT and am running the Insane res firmware from here. This is all on a Biqu B1

Posed elsewhere in error:
I added a smart Filament sensor to my B1 running the insane res firmware and it always signals a runout within 40 seconds of starting to print. If I turn the smart off in the menu the print resumes perfectly. I see that the sensor is really connected to the TFT and not the motherboard and I'm not sure how to diagnose it. is this enabled in the TFT firmware somehow? is there a way to check?