I sent a ticket to uxsoftware to answer this.

While I wait for a response, has anyone else ran into this problem (and possibly found a solution).

With the following RX code

   Track last Horizontal Split for 12 spins to Record "PrevSpins" layout

I receive these results for the following winning numbers
Number 1    Split(1-2)
Number 3    Split(2-3)
Number 8    Split(7-8)
Number 10  Split(10-11)
and so on

The results I would like to receive are
Number 1    Split(1-4)
Number 3    Split(3-6)
Number 8    Split(8-11)
Number 10  Split(7-10)
an so on

It seems Vertical Splits are the default, even though I coded for a Horizontal Split.