I've done a half dozen or so successful projects, most a bit simpler than this one.  I lied in the title, I do have one error, for un-inserted manufacturer parts...there is stuff on the schematic for the purpose of the BOM that is not actually in the 3D assembly.

All connected manufacturer parts are associated with 3D parts in the assembly.

All symbols have manufacturer parts associated in 2D.

All connection points on 3D parts match the connection points on the Manufacturer part which also match the connection points on the symbols.

All wires are, to my knowledge, correctly set up (they've been used in previous projects as well)

No cables in assembly.

No harnesses in assembly.

Single leads only, 18AWG.

All wires connect to a single connection point on each symbol.  No connection points are shared, and no wires are spliced into each other - 100% point to point.

When I click on "route wires" the program chugs for about 5 minutes, jumping into and out of 3D sketch mode as it normally does, except during this process it creates no splines / wires.  When completed, the dialog pops up pointing out that I have manufacturer parts that have not been inserted, but no other errors - which is strange because ALL of my previous successful projects that worked correctly had many errors that did not affect the outcome of the routing.

Anything else I should be checking for?