How did you test this?
OK. When I say that the VFD is not causing this, I mean that ordinary high-frequency current coming through the capacitance between windings and frame are not nearly that large, by orders of magnitude.
I suspected as much. Don't know why.
An analog meter should be less affected by the high-frequency noise, but analog electronic meters (I have a few) are affected by HF noise. Passive analog meters should be immune.
Some kinds of high-end DMM are designed to make accurate measurements of true RMS currents and voltages in inverter-driven motors. I know Fluke makes such meters, and I imagine that they are not alone. I think the key is "true RMS" and a RMS bandwidth that exceeds the chop frequency by a factor. But I have not tried this yet.
You can also open the green wire and put a passive analog AC ammeter in series. Or a power resistor, and look at the waveform with a scope.
I would be tempted to test a few other motors, for comparison, as well.
Joe Gwinn