Why no stair trim against wall in short upper segment?

[GeneDavis]

Here is the file.  https://www.dropbox.com/s/fvp1lver272br2n/Farmhouse w loft.plan?dl=0

 

The staircase has one long segment going to a landing, and a short two tread segment rising from the landing to the second floor.  That second floor, a loft, has a 24" deep floor structure, and the overlook and stair pulpit walls are railing walls, the railing done as 2" fir framing main layer, 1/2" sheetrock one face.  It is that wall that the short upper segment abuts at its R side, the side showing no skirt board trim.  The long lower stair segment abuts and interior floor drawn on floor 1 and Chief generated the specified skirt trim.

 

The staircase is drawn on floor 1 which is the only way I know to do a stairs going from floor 1 to floor 2.

 

Is the skirt trim not generating because the wall the second segment abuts is a floor 2 wall?  Whatever.  I'd like a solution before I go and do the p'solid workaround.

[HumbleChief]

Tried a bunch of options but that upper section wouldn't generate 'Trim Against Wall' as if it simply isn't sensing the 'wall'. Not much help I'm afraid but even in the 3D preview of the stair section it isn't generating the trim, which it usually does.

[mtldesigns]

Is it because its a railing wall?  I have this issue all the time it seams and a Poly has the been the only thing I know to do to fix it.