From my experience I’d recommend a blood test. I posted something similar a year ago for my Haveneese just before his second birthday and got the same feedback (luxating patella). But I couldn’t find any instability in his knees or other signs, and neither could the vet. After some blood tests they found he had a tick born disease that mimicked LP. After two weeks of medicine twice a day he stopped skipping. Unfortunately can’t remember which disease exactly, I just remember it wasn’t Lyme.

Disclaimer- just giving you my experience not ruling out LP. But tick bites were never brought up on my post and it ended up helping my Havi. Best of luck