I just finished Elite Deep Archimedea with all modifiers enabled and without going down a single time. Enemies were level 375 - 400 each mission. No final rewards from Elite Archimedea were received. This is a very frustrating bug.
This isn't just you -- it happened to me and another in my squad as well. For some reason we didn't get the final Elite rewards despite never going down and having all modifiers enabled.
Would be nice to get this fixed due to the long duration of the game mode.