These are my suggestions based on several guesses without having anything to see.
First like a real wah pedal placement is everything. There will be a limited tonal change unless it is placed first in the chain and before any dirt especially.
Second it needs to be dialed in to your specific guitar. This autowah has features to allow you to get the most out of guitar or bass so that said if it is not dialed in for a guitar then it will be less than stellar. Once dialed in however it should be kept right where it is from there on out.
These are the two most common problems 1. Placement and 2. Settings
Barring a build error of course since the voltages are a bit odd (please recheck) and also note this circuit has been a go to for a long while now with no changes other than cosmetic. Make sure all IC pins are seated properly. Re-flow any suspect solder joints. Look for any potential shorting including the solder side of the board. Double check all off board connections and fix or reflow. If you cannot get it going we will need Clear Detailed Photos of both sides of the board! This is a larger circuit and there are just too many things that could go wrong so we have to be able to see it as close as if we were holding it.
Here is a good read.
Proper Q voltages for comparison (all pots full CCW)
Q1: (7.27 – 3.71 – 3.23 – DSG)
Q2: (5.05 – 3.75 – 2.90 – CBE)
Q3: (5.05 – 2.90 – 2.86 – CBE)