@architech
I've tried to reproduce your issue with U shape with landing.
1. I'm not a math like I'm not an architect but

Distance=2.70. Stair count=18 (two flights of 9 stairs; U shaped with landing; landing counts as one stair) Stair height=15 > because 18 x 15 = 2.70.

The U shape staircase (at this moment) accept an odd numbers of stairs and one of them in the landing.
So 9*2=18; 18+1=19 OR 8*2+1=17.
2. The plugin warning you about the incorrect input number (in red) but you choose to ignore it.
Consequently the plugin ignore your input (18) and use 19 with the accordingly results.
3. The last stair elevation is where the last step end (at TOP).
4. You don't need to hide baluster like I've did because you have the last stair elevation.
5. There is 3 concrete texture in library name as Wall concrete.


To have exactly 2.70 the Stair height have to be 15.89


The concrete one is created with your settings.