Dude congrats on the kid!
Sucks that nothing is helping the knee. Wish I could be of some help. I know you tried KOTG and diving into the theoretical side.
Probably a last option scenario kind of thing, and not even sure it would help but something I have been thinking about is getting one of those fancy $1000 DonJoy braces they prescribed me when I tore my PCL. Then my mechanics made it to a reasonable level, i stowed it away, and then my mom threw it out. After delving deeper into how the body works and realizing just how much compensation mechanics have happened because of the PCL tear, really wish I still had that brace. I'm not entirely sure what injury you have, but it might be something to consider, maybe a professional could recommend you something.
I think it's kind of interesting that playing bball doesn't irritate it but jumping does. I'm sure you've tried some stuff like this but maybe some specific sessions where you do some athletic movements and try to figure out what specifically puts extra stress on the knee and how you can try to alter mechanics to adjust for that? examples - jumping DL with a more frontal jump plant vs a more side plant , or jumping SL with more hip extension vs knee flexion? And then maybe, if one jump technique doesn't seem to generate a lot of power but is ok on your knee, maybe that would be more trainable than a technique that hurts your knee? Might not work at all but just thought I would throw it out there.