I've had reports that this bug also affects standalone.
Unable to reload guns. Can't chamber rounds, reload magazines, put magazines in guns etc. Doesn't matter if I'm trying to combine the items or using the default hotkey "R". I am able to shoot if there was ammo previously in the gun.
I think the way to reproduce it is to have a melee item in the hands and attempt to drag and drop a gun or magazine to the hands through the inventory screen.
Sometimes you also can't put the gun or magazine in your inventory. Double clicking, dragging into the slot or onto your player doesn't work.