I set a diagonal set of mine tracks and the cart kept turning around.  I removed the diagonal tracks and went to a simple corner and the cart worked.   At the next corner the mine cart turns around.  I attempted to break and reset the track in by laying it in different orientations and problem persisted.  I placed a switch and when turned on the cart would turn one direction, but would be returned when trying to to the other way.  This problem should be easily reproducible.