Sorry for so many injury posts, but they're all different injuries

There's something weird I've had for a few months. I think it's a "domino effect" injury caused by my main injury.

Basically, when I'm sitting in a chair for a while, if I bend my knee from 90 degrees to straight, the kneecap sort of tracks weird -- kind of like it jumps from one position to another.

To resolve this issue, I place my hand on the kneecap and push it inward (medially) while extending the leg, and the kneecap audibly pops, and then the problem goes away for about 30 minutes (I can extend my knee normally during this time). Given more time, the problem repeats itself.

I feel no pain with any of this, and I haven't ever had the kneecap slide out of place or anything. And it doesn't feel like it's out of place before extending or after.

The problem is particularly prominent when I go out to ride my bike. For the first few pedals strokes when my leg is at a certain position, my kneecap "jumps" just like it does when extending it while sitting in a chair. To fix it, I have to unclip my foot, extend my leg and press the kneecap inward until it pops, and then the rest of the ride it's fine.

Does anyone know what condition this is? I've had little success Googling.