New board
see https://sourceforge.net/tracker/?func=detail&atid=805242&aid=3018513&group_id=157793 for reference - this is already fixed and will be part of the 2.3.1 patch - thanks for reporting
I can't enter all room on a special UFO, as there is no path present. This also means the aliens are stuck on the second level of the ship, but will descend to ground level when a PHALANX soldier is near the door. Neither the soldiers nor the aliens can walk through these doors.