Floor Plan Cut Plane limits
The Floor Plan Cut Plane can never exceeds the limit of the story range.
If it's height is below the story(-xxx) it will be set to story 0.
If it's height is above the story range it will be set to the story height.
In the picture we can see how 'Floor Plan Cut Plane' affect on different wall heights above the story range.
Note: If you set the stories heights (e.g. in Story Settings Dialog) it can affect on the floor plan cut plane if it is beyond the new value.