So I decided to use the new event as an opportunity to level up some of the archguns I have in my inventory that I haven't levelled yet. I've used an unranked larkspur in about 5 half-hour runs for the endurance Orphix Venom mission and its still Rank 0 when I view it in my arsenal. This being said, during the mission it is saying and showing that my archgun is actively levelling up while I'm running the mission. But, as stated, all gained affinity is lost after I have extracted from the mission. Here's hoping that this will be an easy fix.