text: Ok, so I checked it and the elevator isn't visible at all at level -1 (B-Ebene). 
  Here are the pictures:
  View from level -2 to elevator: https://hohl.tru.io/s/Ms4Kq6nnPXxoFie
  Same viewing point and direction just one floor up on -1: https://hohl.tru.io/s/sfZ6dAbAkrLqbaT
  Another angle on floor -1: https://hohl.tru.io/s/P28FtdiTK8wD84X