Me too, similar looking map, about the same proportion of gigantic non-aligned area - slight difference in zones. Also on a world with large quantities of alien wildlife.
Playing with complete fog of war, on Round 10, I sent spies to one of the non-aligned regions nearby my starting position, and the next round I found I had at least some recon on pretty much the whole map except minors and majors.
In my case it doesn't seem to be a single zone per se. You can see the "Tool Compound" zone partially highlighted, and there are other non-aligned zones that exist besides it on the zone list, but it appears the "Tool Compound" zone doesn't have a border between it and the other non-aligned zones. Later on in the game it went back to normal and the zones had proper borders again.