I did a version of that, it’s here GitHub - holmesrichards/MFOS-SVF: Eurorack adaptation of the MFOS "Oldie But Goody" state variable filter .
It was one of my first PCB projects and I would definitely do some things differently now. I had the two PCBs in separate KiCad projects. Like you I was using global labels for the power rails — it’s much better to use KiCad’s power symbols, for better readability and to better enable use of the electrical rules checker which is valuable in locating schematic mistakes.
It would also improve readability if you used descriptive labels like “SIGNAL” and “OUTPUT” rather than “A1_1” and “A1_4”. Though eventually I figured out how these labels just connect to similarly named labels nearby.
If there’s a schematic mistake I don’t see it, then again I just got up. Have you carried out all the recommended checks here?
Check also the connectivity from the transistors to the power rails and ground.