Greetings,
I just started my account 3 days ago and I wanted to play arena, but it said that I needed to get all classes to level 10 which I did tonight. Unfortunately, I still can’t access to the arena mode. I guess it has something to do with a bug with the new demon hunter class. Who is Arenaboi without arena? 
Please help!
I’m having same problem. It’ll be probably fixed once new class is out, but it’s still annoying.
Next week, when the Demon Hunter class releases officially, this problem will auto-fix itself.
Someone reported yesterday that this was resolved for them:
Completing the Demon Hunter prologue may be enough to resolve this issue, even though the class isn’t officially released.
Did anyone figure this out? I still have this problem and all 10 of my classes are above level 10. I’m locked out of arena mode and duels.
have you completed the DH prologue and unlocked DH?
Yes. I figured out the issue. I didn’t have a deck built for the Druid class so I hadn’t been using it. It’s only level 2. Thanks!