For some reason I still can not mod certain weapon parts. For example, I can't build the overcharged overcharged capacitor for the institute auto pistol. I have all the parts and and science 3 is required. I have all 4 science perks, but it still says I lack the requirements to make this item. I don't get it... Any help would be greatly appreciated!

I have noticed from time to time that I can't make something if I am about to use the last of a required component.

example say something needs 10 leather pieces and it says I have 10 leather pieces left. It won't let me use them until I have 11 pieces of leather left.

Just a thought. And are you on the PC or console?

I have also noted sometimes if you add an item through a console command, the workbench does not notice.

I'm on ps4. I'll have to double check on the inventory items. There might be one that is lower than double the needed amount.

Sometimes, if you have only the required amount, it glitches out and won't create it. Happens a lot with construction mostly.

One thing worth noting is that sometimes the list of materials needed to make a mod is longer than the space available in the crafting interface. You may need to scroll the list down to make sure that you actually have everything; something at the bottom of the list may not be at the required amount. You're probably aware of this and have verified it, but I mention it just in case.