Fireworks not stacking correctly

Fireworks not stacking correctly

I thought fireworks were supposed to stack anyway you want under 64.

Instead it glitched and would not stack (not even just a minimum of 14!!!)

1: Create fireworks (mine were light green, cyan, and purple)
2: Try to stack a color (in my case purple) into three even stacks
3: It should start to glitch when you put 17 into the first stack