Guardians Not Spawning Correctly In Drained Monuments

I have recently drained an ocean monument on a newer world (After the Aquatic release, not in the BETA.) and the guardians are not spawning as they should. I get a few random ones here and there, but it's definitely not working how it should. I know how the mechanics work and I've triple checked everything many, many times... Please fix this. I don't wanna keep playing a broken version of Minecraft. Draining a Monument is a good chunk of work, we shouldn't have to deal with this.