When you pick up weapons from dead soldiers local to the dedicated server (any enemy AI-group) using the hand symbol, you take the new weapon and put your old one + ammo on the ground, which will then just disappear after half a second and will be gone forever!

-Only the weapon disappears, not the ammo.
-As soon as this bug occurs, it will happen every time you use the hand symbol during this mission.
-Affects rifles and launchers.
-It does not happen when you use the inventory menu. In fact you can safely use the hand-symbol to swap weapons after you switched them via inventory menu first. Only true for this specific weapon, the next one will disappear again.
-This is not related to any mods, and it also happens on the official ZEUS-servers.
-It also seems to affect the picked up weapons somehow (empty magazine and disappearing ammo, even when the AI soldier haven't fired at all)

This bug can be very frustrating, since you often use the hand-symbol accidentally, resulting in a loss of your precious gear and leaving you with an empty standard rifle with iron sights. ;)