I have a Surface Pro 4, the Surface docking station, and 2 additional monitors. The second (middle) monitor is marked as “primary.” So the order of display on my desk is (right to left); 1. Surface 2. Primary monitor 3. Third monitor.
When using all three displays, Atlantis runs and displays in the primary monitor.
When the Surface is not attached to the docking station, Atlantis does not recognize that there is now only the Surface screen. Atlantis runs, but does not display on the Surface screen.
With the last one or two big updates from Microsoft, Atlantis now will display on the primary monitor - meaning if Surface is not attached to the hub the Surface itself is now the primary.