I completed the area with a partner but when I went to collect the evidence only my partner got the evidence. I went back, but it saved it as the same amount of progress with everyone beaten, and the evidence not there. What now? :?
First off, there is nothing that you physically have to collect. Defeating the grub will automatically "give" you the evidence.
However, if you did not pick up the quest before entering (i.e., porting to your friend), and bypassed the earlier quests inside the dungeon, then you would not have progressed to the point where beating the Grub would have given you the evidence.
I have this problem too! I just did the entire dungeon. I was defeated while we were killing the last minion (we killed Grubb first) but fled and teleported back to my friend before he died yet didn't get the item of proof! Is there anything that can be done about this or is it just bad luck?