Yeah, thats a lot of pedals to run through! It turns out that stacking buffer on top of buffer on top of buffer can go awry just as easily as a string of true bypass pedals! (sorry, Bongo!

) Eliminate pedals one at a time to see if there is a "smoking gun" culprit. If it's a case of a cumulative overall loss, you'll need to come up with a whole new strategy of signal routing!
When you get into that many pedals (and notice volume and/or tone loss), it's time to seriously evaluate whether you want to use that many pedals- or invest in a thought-out switching strategy that preserves your tone.