Persistent background signal when recording

When recording from stereo mix, as soon as I hit record I get a background waveform of around 36hz at -20db being recorded.  This appears not to affect the recording other than by making the waveform look wrong.  On playback it is inaudible.  This doesn't occur when I record using Audacity.

I've spent hours talking to AI about it and tried many ways to fix it but to no avail.  Any thoughts?

I'm using an HP OmniBook 5 WIN 11 with Realtek High Definition Audio