I have seen strange behavior with hinges (both in 2.74 and 2.75). I have a table which is attached to the ground using a hinge constraint, to enable it to rotate. The table can have any number of objects attached to it, also using hinge constraints. I rotate the table by attaching a kinematic object, via a hinge constraint, to the table and move it around. With 1 or 2 objects, it works fine. With 3 objects, one of the objects (it almost seems random which one) will follow the movement of the kinematic object. That is, as the kinematic object moves, the object attached to the table moves in exact synchrony. Meanwhile, the other two objects are stationary and the table rotates, as it is supposed to do. When I release the constraint between the kinematic object and the table, the object that was moving around snaps back into its original position. Now, it gets even weirder -- with 4 objects, everything behaves as it should. With 5 objects, it behaves as it did with 3. With 6 objects, *two* of the objects move as described above. Haven't tried with higher numbers, yet.
Any thoughts as to what might be occurring, and how to fix it?
Thanks.