I was using /maspawn with no issues after the wipe, up until today. I keep getting this message when using /maspawn, though noting is actually spawning. Trying with Boxes, Photo Frames, Signs etc.

Are existing entities spawning, with only the new ones not spawning, or are all entities no longer spawning? What happens when you reload the plugin?

Yes, exsisting entities are spawning, just unable to spawn additional entities.
Reloading the plugin / restarting the Server brings back all of the exsisting entities, though same behavior when trying to add addtional ones via /maspawn.