i havent got time right now to look at your file, but you could just model this as a sweep quite easily, using the floor edge as your sweep path.

Congrats, you found a bug....
The problem with this is that Revit sets the thread thickness to 0 in Monolithic Stairs. Combined with a curved stair this creates a bug. If you apply a thread thickness in the type properties you will see this effect to decrease. But, the stairs will become thicker as a whole. This can be undone by setting the Landing Carriage Height to 0. The problem is that the Carriage Height in your stairs is only 50 and you need to set the stairs thickness to a minimum of 130 to loose this effect. This can be diminished by cutting the stairs in different segments.

Another solution would be to create the stairs by sweep, as described above by Elton.