Thrifty Tinkerer exclusions not listed

Hey! I just received a ticket about Thrifty Tinkerer where my players were expecting to receive Explosives back while crafting C4. Skill Tree, by default, black lists explosives, gunpowder and sulfur from this skill however it is not listed in the description like it is for Harvesting Yield. I've manually added this myself however that's obviously not ideal so I was wondering if you would be able to add it in officially? 

Thanks!