Items wont stack

In my fantasy mod, I have multiple gems and ores. I was testing the item drops from ores. The 3 gems stacked together, but it separates each drop from each ore. The 3 gems that come from one block stack into one stack, while another drop does the same. The player is not able to stack these manually in the inventory, and once you separate a stack, you cant merge those items anymore. I have max stack amount at 64 and the item drop from each ore block is 3. Really new to MCreator.