Blaze Spawner stopped spawning

While opening up the area around a nether fortress, I noticed that the blaze spawner no longer spawns any blazes. I've checked in the surrounding area and barely any mobs exist. I even lit the parts of the nether fortress to limit spawn locations and still nothing. Lastly, I tried changing my realm difficulty to peaceful while standing within spawning range of the blaze spawner, then back to normal. Still nothing. I am in the process of filling the opening i was creating, but this still doesn't seem right since no "mob caps" seem to have been reached.