My team and I have tried this multiple times with different amounts of people. When we went in with 2 people, we tried taking as much cargo as possible only to notice that it disappears when trying to warp back to ship.
If that is an intended game mechanic, we also tried taking a 3-man team, dropping all of our inventory and taking all 9 of 9 cargo cases. At the push of the button, no cases disappeared. We managed to take all our cargo cases and the weapons we had dropped back to the ship. At the end-screen, no additional bonuses were given for obtaining 1 required cargo case and 8 additional cargo cases. Somehow we didn't fulfill all of the bonus objectives on the final mission even though we did everything within timer, obtained all the loot and fought off all the enemies on 3.0 difficulty.
We tried another map, Vault Breach as well in Icarion Reaches 4.0 difficulty. Same thing occurred. No bonus rewards.