I've been staring at this for 5 minutes and I can't find where the mythical stereo interleave button is. The track is currently operating in mono (or at least it's merging the 2 Guitar Rig channels into 1) and I need it in stereo.
 

 
I'm sure the button used to be visible on here in 8.5 (which is where this project originates from), but I can't find it now.

It's in the track inspector now.

Ah, thanks. That's annoying, as I never use the inspector for anything else and have plenty of free space in track view, but I guess I'll live.

It's also on console view.