I wish I could offer you my input, but the devs seem to think that it makes sense to screw over half the player base by excluding them from the event for "testing purposes" (since they seem to think that having a smaller sample size is better for some reason), so I don't even have access to the event at all.

you may need to clean your cache but first spam arena. The one I did last time I did it in one go. oh and see if the event cards have steroids cuz that's what I used.