SAme issue here! if i use the wah pedal and them return to use de expression as a volume pedal... the behavior is a complete mess... if you have the expression for volume off.. and move to a different snapshot you will have full volume up of that snapshot... but if you press de to have full volume and return to the snapshot that you cut the volume... them you will have volume off... i think there is a bug...
how I resolve it... for copy a new volume block.. but it return to the same behavior after using de wah...
so... i guess there is a bug in there.