The game does not let the players place elevators at all, no matter where I try to place it, it doesn’t say invalid placement or any errors, just doesn’t place it down.
I have flotsam buildings high up on couple of redwood trees, I use horizontal elevator to get to another building and then vertical to get down or up. I always pick up the elevators after use and I had no trouble of placing them today. I picked them up and placed down several times with no problems.