Animation entering from wrong side

Using jquery-sortable with Bootstrap 3. Have set up your example with two lists and the animation shown on dragging between. Works great except, strangely, after I drop into the new list (say left list to right list), it animates the clone as if it were being pulled from the other side (it blinks over to the right of the right list then animates in).

Any idea why this might be? Using col-4 for each list div. Is it an offset issue or something with Bootstrap 3.0?