Please note that the weapon ammo system in Destiny 2 may work differently from what you might be used to. If you're talking about your Warlock on Steam, you currently have two weapons equipped that use primary ammo ([armory]Psi Cirrus II[/armory] and [armory]Riskrunner[/armory]). You have no weapons that use secondary ammo. You have one weapon that uses heavy ammo ([armory]Crooked Fang-4fr[/armory]). Just because a weapon is in your Second Slot (the Energy Weapon slot) doesn't mean it uses secondary ammo. You can see which ammo type a weapon uses by looking at it's info card when hovering over it. Those that use Primary (white) Ammo Bricks will have a white box with I in it. Those that use Secondary (green) Ammo Bricks will have a green box with II in it. Those that use Heavy (purple) Ammo Bricks will have a purple box with III in it. With your current set-up, you'll only be able to pick up Primary Ammo and Heavy; your Secondary Ammo will always be full because you have no weapons that use it, thus making you unable to pick up the green Secondary Ammo Bricks. If you're out of ammo for your [armory]Psi Cirrus II[/armory] or [armory]Riskrunner[/armory] , you'll have to pick up a Primary Ammo Brick (white), since they both use Primary Ammo.