hey bro. there should be no reason for this to not reach unity gain with or without active pickups. i have a few active basses, one that i can switch from active to passive, and when it's in active move i overload the effect and push it into more distortion territory then OD. i've got three stupid ideas to try and see if it's the active bass or the pedal or something else going on.
1. keep the amp, wiring, and the pedal chain all same, but switch to a passive bass, then try a different active bass.
2. try putting another pedal in front of the BBBOD, any pedal without a buffer. use the active bass causing the problem.
3. try putting a buffer or buffered pedal in front of it. use the active bass causing the problem.
i'm wondering if it's the issue of impedance of this active bass or something.