Have built a zombie farmer from a naturally occurring zombie spawner. Worked fine for months,  after the most recent update it has now stopped spawning mods. If everyone exits the realm it will work perfectly fine UNTIL we must sleep through the night.  After sleeping the spawner stops spawning any mods altogether. I have tried moving my bed far enough away from the spawner that it should not effect this but that did not help,  it does not seem to matter where you are if everyone in the realm sleeps spawners turn off until everyone exits.