'Track To' bone constraint problem (bug)

The Track To bone constraint goes crazy, moving around when more than one is in the scene. But when I parent an object to the offending bones(the blue planes) then the problem goes away. Just delete two or more of the blue planes in the scene and move the player a little bit(the camera on the player is being tracked) and you will see the problem. Can anyone replicate this so I can know it’s not just me? Or perhaps there’s a simple mistake I’m making…

BTW, I’m using 2.75a

Attachments

Bone_Constraint_Problem.blend (793 KB)

I see your blue planes are “bone” parented(CTRL+P+bone) while your red cubes are “object” parented(CTRL+P+object), I don’t know what else is causing the twitching but it seems bone parented object can stabilize the armature

Yes, I know bone parenting stops them from bugging out, but that may not work in every situation. Surely this is not the way it’s supposed to be.