Steps to recreate:

  1. File->New
  2. Navigate to a blank "Captain blue" screen
  3. Screen->Doors
  4. Select at least one of the four door types (whether it's North, South, West, or East doesn't matter)
  5. Click 'OK'
  6. Observe Captian Blue is still there
  7. Place a combo in the middle of the screen
  8. Observe now the door(s) appear on the screen