Fill tool issue, possibly walkway related? (NOT related to desert issue) (Workaround found but is slow)

[Sakata-MC]

Trying to use fill to stack floors of my stairwell. I can copy/paste fine but fill is the right tool for this job if it would work as expected. Ignore the foundations (other than as measuring marks), they're not part of the design, but I was using them for guides while trying to debug this. So the gap here... isn't supposed to be here. I can use copy /paste tool as a workaround, but really wish there was a repeat option like fill for it... paste x iterations with a multiplicative offset.