This mod is preventing normal zombies from spawning in a spawner when in the Taiga biome. This behavior should only prevent zombie spawns in the world, not altogether from spawners. It does successfully replace them with Frozen Zombies, but it doesn't work with the spawners and instead prevents their spawning.

Closing This issue, it was being caused by something else and not this mod.

Indeed, the mod only removes natural Zombie spawns from Biomes. :)