When I parent an object which is tracking something, to something else, the child object moves or rotates, whereas it doesn’t do that when no track contraint is defined.
In this blend file, the middle cube tracks the right one. When you press ctrl-p, the middle one becomes the child of the left. It also jumps location. When you remove the track contraint first, and then parent, then all is fine.
In a landing gear rig I’m making, one particular object rotates when giving it a parent, whereas another moves so far away, it is outside the clipping distance of my edit view.
Is this normal behavior, or it is a bug? In any case, it’s kind of annoying, because it means I have to redo all the tracks of my landing gear in order to make all the parent relationships.