Spawner blocks can spawn entities mid-air, on top of glass, or even on rails. This works for many different ground-based mobs. While I believe this is WAI behavior, I could not find an explicit source to back that claim up. The 'spawning on rails' part of this issue is covered in ...
Issue Links relates to MC-141301 Illager patrols spawning on blocks mobs shouldn't spawn on, such as slabs, carpets, stairs, etc. Resolved Activity All Comments History Activity Transitions There are no comments yet on this issue. People...