Blaze Spawners are simply not there

I was on my survival world on peaceful and I went to a fortress and found a blaze spawner spot and there was nothing there just air where the spawner should be. so I turned it on easy and it started spawning blazes like normal but there was still nothing there.

Seed: chancecash

location: 336 78 -112 location of the fortress but not the spawners just look around it affected all of them