I feel like this has happened to me before, but I'm stumped.

I have two channels, two voices, each are organs and neither one has Mod Wheel. I've gone into the Controller menu on each and everything is checked. I went into Utilities and I didn't find anything that would relate. I've tried toggling each Voice to "reset" it, long ago, but no change.

I've Erased all troublesome Events, like CC and EX in the entire Song.

When I leave Song and go directly to the Voice block the same Voices have Mod Wheel. So it's not a hardware issue.