There's most likely a flaw in this proposed CRF, as to be expected with my "work," but here goes anyway.

A loop of six haps (xo6ox tower) goes through the polychoron, manifesting as columns of three haps in each of the two identical "halves." They make contact with the two hexagons of the "middle boundary." Six peppys connect to each of the "top and bottom" haps with one triangular face, while their pentagons connect to the pentagons of the middle boundary. 36 tets fill in all gaps.

"Central" hap of one half highlighted:

"Top and bottom" haps of one half highlighted:

Like D4.8.x and other known CRFs, it has a near-miss Johnson solid as a middle boundary. This middle boundary is a dodecahedron with two antipodal pentagons replaced with hexagons, and two new pentagons added. (D4.4's middle boundary is like a gyrated, rectified version of this, in case that helps.)

"Top" view:

Facing one of the pentagons:

I checked and double-checked all the dihedral angles, and didn't see any in excess of 360°. (There were some in the mid-350s, though...) I checked CRF-list.xls, and didn't see any polychora with 6 haps among their cells.

So, what's wrong with this one?