Legendary perk ammo factory not working

I don’t know if I’m mis-understanding how the perk works but I have it at level 3 (100% more rounds) and I assume that means if I make 200 rounds, it gives me another 200 rounds to make 400 right?

It has not worked once since starting the game again last week and I’m now level 81 on a new build. Im on xbox and previously played a year ago on ps5. Am I using the perk wrong? I also have the Ammosmith mod and the super duper maxed but haven’t seen the legendary one work yet. Thanks in advance