So I have been grinding this event pretty hard since i made my return back to destiny in the Festival of the lost. Everything was going as intended until i was starting to run out of space for consumables so I put my 80+ "A gift in Return" boxes into my vault, finished up my grinding and logged off thought nothing more on the matter. I log back in today and all of my "A gift in Return" have disappeared from my vault. Checked my inventory...nope not there either. Did a test got 1 "A gift in return" box and deposited into vault went and did an activity came back still in vault. So i logged off and logged back in and low and behold it is gone. Ran another test just to be sure...same result. I feel defeated for grinding so much and not opening those packages immediately. TL/DR: Do not deposit "A gift in Return" into vault you will lose them once you log off.