It sounds like there's some disagreement on whether your muff pedal is mid-humped or mid-scooped?
If your guitar is getting lost in the mix then the most common explaination (At least to me) is that it doesn't have enough mids. Your low and low-mid frequencies will get mixed in with the floor drum and bass guitar, and your high frequencies will get mixed in with the hi-hat, crash, etc etc.
The point is in a usual band mix the most amount of sonic frequences left unused is the mids, and that's how a guitar cuts through, by having lots of mids.
I think I have that right as I just read some papers written by a prof from a well-known music institution, hope that helps somehow.
If I were you I'd try to borrow a EQ pedal and see if it could remedy your problem.