Furnace Split wont split in Large Furnace

Check your stack sizes very Large Stack sizes do not play nice after the updates with FacePunch.

I do have stack size on, its fine with other items campfire, small furnace, etc its just the large furnace

Sounds like a plugin conflict, easy way to test is unload all plugins and leave Furnace Splitter and test, if it works as it should then you have a plugin that is causing an issue. You will have to then load a few at a time to see which one is breaking it.
Troubleshooting 101

I changed the stack size for wood, metal ore, sulfur ore and hq ore to 10,000

MechWarriorZero

I changed the stack size for wood, metal ore, sulfur ore and hq ore to 10,000

I know on my servers I have the stacks set  for Ores & Charcaol set too 100,000 and Wood at 250,000 and splits fine in the Large Furnaces no issues.

Have we found out which plugin it is? Will be testing it here soon I guess if no one has figured it out

Merged post

Okay figured out which one it is.

Stack Size controller - https://umod.org/plugins/stack-size-controller