in my opinion, Graphisoft made some decision on this tool - also on the railing-tool, not to get too much vectors in 3d - they tried to simplyfy 3d too much - with the result, that "borderline-cases" like Your example cant get to reality with ease.
Also problematic: Graphisoft tried to merge several calculation-models to create stairs what causes many limitations, that would not be nescessary in reality. Better would be one simple way for calculate the stair:
Suggestion:
First - divide the hight-difference through the maximum hight of the riser - take the next integer for the number of steps. Calculate the hight of the riser from this number of steps - take the length of a human step (63cm+-), subtract 2x riserhight to get the length of the stair-step. Divide the Walkingline through the length of the stair-step. This dividet Walking-Line has to be the "mother" for all further calculations..
Graphisoft tries to make much more possible calulations and gets into trouble with this..
Normal stars can be made with some simple working - steps but when you want to get special small spaces for stairs to work, you get in trouble.
For such cases - the older stairmaker was much easier to use - you got much closer to the wanted result - but with no flexibility at all. It was not a real good decision, to "kill" the old stairmaker complete.
The old idea, to select a type of stair and then set the measures was better than the now existing solution - better because much faster.
My solution: implement both possibilities! Add the old stairmaker as addon - which was the case anyway before.
AC5.5-AC27EduAut, PC-Win10, MacbookAirM1, MacbookM1Max, Win-I7+Nvidia