We did onslaught floor 65 and we beat it and she did not receive her cosmeticsExpected Results: She was suppose to get the floor 65 cosmetic and she didn’t?
Happened to me aswell. Cleared floor 38 and havent gotten my cosmetics.
Same for me I did not receive my cosmetics for floor 38 after doing it solo and with other people or after redoing another floor or restarting the game.
It seems there is a problem with the prerequisite for unlocking the Onslaught and Prestige challenges. Unfortunately there isn't a quick fix we can do, but everything will be awarded once a fix is released.