I put a toolkit together opened the menu then closed it to get a heavy weapon, came back with the heavy weapon and the tool kit didnt display the new weapon only the old one i didnt have anymore an...

TOOLBOX ISSUE. Error in weapons available for upgrade when you have opened the toolbox and then collected another weapon.

when you don't upgrade a weapon at a workbench, pick up a new weapon on the same slot and you try to take an upgrade, it show the previous upgrades and the previous weapon you had

Weapon upgrade bench not allowing you to upgrade a weapon that you did not have prior to you interacting with it.