Erratic Gizmo

Is there a setting somewhere in Constructor that aligns the gizmo to a selected brush. Sometimes the gizmo centers on a selected brush, sometimes it is way off center. For example I built a simple rectangular building, four walls, floor and ceiling. I used CSG Subtract to cut a doorway into the building. This made three brushes out of one. Now if I select the brush on either side of the doorway the gizmo centers as if the original brush had not been divide. I would like to have it centered on the selected brush, if possible. It actually gets worse, if I select the small header brush over the doorway the gizmo centers vertically on it but jumps out about 4 units away from the brush horizontally.

It seems like the problem is even worse with larger brushes. The gizmo is often so far from the brush that it makes the gizmo useless.

Thanks for any help on this.