Ok my cables shouldnt be the problem i use 2 sets both made by Ron from RJM Music for me and they both did the same thing.

So if i understand u correctly if the expression pedal works in normal mode it doesnt guarantee itll work in the split Tap and Exp mode?

I checked the inside of the Dunlop X and its pretty much wired through a small pcb between the pot and jack so ive no idea which goes to the ring. Has anyone had experience in using Dunlop X with the Tap? Does Dunlop X work? I wanna know before i sell it to get another pedal. Ernie Ball Exp 25k definitely works right??