I have the same issue. I finally beat Kamino tonight, knowing that was the last one I needed on attack. It still says 4/5 for me on the challenge, and I like, this is the last one I need to finish off the Multiplayer group of challenges. When it didn't show complete I went through all the maps ensuring I won on all the others just in case. Tried restarting the game a few times as well. Just stuck at 4/5 for The Aggressor.
I have the same problem, after winning KAMINO, the 5/5 challenge is displayed, but the collection still shows 4/5, the same problem I have with The Defender, that prevents me from the complete milestone edition in multiplayer ☹️ Martin (Europe)
