Wall effect and ceiling effect certainly exist in my house.
My explanation is that the presence of the wall is a restriction on the air flowing into that side of the rotor disc, not only does it block the free flow of air because it's a wall, but because Reynolds painted it and air sticks to it.
The rotor disc keeps 'pulling' air in though, so any that comes from the direction of the wall has to be accelerated into and through the gap between wall and rotor, which reduces the local pressure.
Consequently the higher pressure on the opposite side blows the rotor towards the wall.