Release Note: v4.37.40.2 | Dated: 1/16/19 | Addressed this problem.
The button for entering fullscreen does not currently support toggling back and forth between the two views and is expected to work in the next version of illumin8 as intended.  If you find yourself stuck in the expanded view, hit the home icon in the lower portion of the screen to return home, and select the blue scene icon on the home screen to return to where you left off with your transformations.