‘This control does not exist in your session’ when using modifier value to select track

I’m pulling my hair out trying to troubleshoot this. I’m not sure if it’s me or a bug.

When I use a modifier value instead of a fixed number to select a track in a volume mapping, I get the error ‘This control does not exist in your session’ in Live.

I created stripped down controller, script, and reaction and still see the same problem. In my stripped down testing, I’m just setting the modifier value directly on script initialization: self.set_modifier_value("m2", 2)

Any suggestions or might this be a bug? Thanks!