Ok I've had my Metal Muff pedal for about a year and recently I've noticed it only works when I hook it up to my amp through another pedal along beside it.

For those who need a visual aid to understand it better:

amp --> metal muff --> guitar = DOES NOT WORK

amp --> metal muff --> other pedal --> guitar = WORKS

Does anybody know what could be wrong with it? It's still completely useable, but it would just be nice to be able to hook it up without needing another pedal with me...