Openvino 4-Step stopped separating Bass track

[organoman]

Audacity v3.5.1, Windoze 10

Last night, Openvino 4-Step worked just fine.
This morning, the Bass track is a flat line!

It doesn’t matter what song I try it on or whether a stereo or mono track.
Vocals, Drums and Other Instruments are all there and play okay.

I haven’t installed any new programs or made any system changes since last night.

Any help would be apprecated.

Alan

[organoman]

UPDATE

I reinstalled Openvino. I still get a flat-line Bass track using 4-Step on a stereo mix.

What DOES work:
If I separate the stereo tracks and then do 4-Step on the two tracks, I do get a Bass track – but it takes twice as long! Not happy with that.

Anybody run across this issue?

Alan