Need help with tracking points that disappear

I’m currently working on a demo project where I rotate my arm and overlay some 3D object. When I try to solve object motion, it says I need 8 active tracks on frames. However, I looked on all of the frames and there are always at least 8 active tracks, though some disappear and reappear (See pictures). What do I need to do to get a good track?

P.S. If it helps, I only use part of the clip in the motion tracking.

I believe it says that you need 8 active tracks on KEYframes, which would be your ‘keyframe A’ and ‘keyframe B’. Check that those are set up correctly, i.e., that at least 8 tracks are visible on those 2.