4PM filter - Extremely low output

Hi! I’m working on fixing up a project I had for the past year and a half.
Basically, I’m at a point where I’m clueless as to what could be the cause of this issue.
I can hear a extremely faint output on the jack. I’m talking -50 dB or more.
I checked the voltage, no problems there at all. The issue starts arising when I probe the sound.
Around the VC2164, no issues. I can hear all 4 poles. Then, going a bit further, I can still hear it.
Then, I can hear the oscillator on the lower end of R19, R20, R21. Nothing on the upper end that goes together to go to the TL072.
Checking the resistor values, they are good. The TL072 only shows voltage on the test points though.

Could it be that TL072 not helping with the Amp at all? Or should I look towards the LM13700?

Bump!