Overpopulating with custom mob spawns.
I added in a custom mob spawn for thaumcraft:cultistportallesser
I set up all needed things like spawn limit to only 4 portals I set up some extra spawn rarity like for the merchant from -1 to 30
And I also set it up so it can only spawn near a rift (the black thing on the picture)
But the spawner completely ignores the spawn caps I set this is definitely more than 4 portals.
I than tested it with letting all settings stay the way they generated and even turned of the extra mob spawner function (set it to false) and then only changed the spawn cap from -1 to 4 still the same result is it some kind of bug? Or does the cap just not get that there is a mob of this type already near?

Hello! I know this is an old issue but just in case this helps anyone else: you can use the custom spawns from Multi Mob in conjunction with the mod In Control to set a working spawn limit. You can also do some other fun things like have them spawn with certain items or tweak their health and damage, so they work pretty well together :)

To update this bug, overpopulating is not limited to custom mob spawns.

I added vanilla creepers, zombies, and skeletons to the file then set a limit of 5 mobs for each and turned:
I:"Tick delay between spawns"=10
to
I:"Tick delay between spawns"=1

The result was still more than 5 of each mob spawning around me on a 1.12.2 Forge server.

multimob-1.0.5
spongeforge-1.12.2-2838-7.2.2
Forge Mod Loader version 14.23.5.2847 for Minecraft 1.12.2

Hello! I am having a similar issue. I believe you want the tick spawn to be a larger number? It seems to make things spawn less for a while, at least... the spawn limit thing seems to be totally ignored and I'm looking pretty desperately for a fix!