Hi Chris,
I was wondering why deleting and installing floor made the difference. I tried lowering the existing floor thinking it was conflicting with the walls, but no change occurred.
Then I looked closer and saw the outside perimeter of the floor was falling in interior center of the exterior walls. In Envisioneer the center of the walls are special points of reference. For instance, flipping a window is based on that magical center of wall line.
So, I left the floors as drawn but went around the whole building pulling each node out past the walls. This moved the floor edge off center. All the interior walls connected immediately.
No need to lay out floor edges so far away, on perimeter works, but just not dead center.