When moving a stack of multiple units, the unit with the least move points determines the distance the stack can travel as a whole (as expected).  However, after the movement is complete the leader of the stack, and the units having the least movement have their movement points reduced to zero.  Other units in the stack will still have their full movement points remaining (as if they had never moved themselves).

It looks like the stack leader's movement points are broken (should retain remainder of move points I imagine) as well as the 'other' units movement points (should be reduced by appropriate amount of move points).