Unable to play arena

All my hero classes are level 10 but still unable to unlock the arena.
Already tried redownload the game, didn’t work.

Demon Hunter has been added to the game as a new class. The class will officially unlock on April 7, but it has already been added to the game.
The check apparently, erroneously, already includes Demon Hunter when checking that “all classes” must be level 10.

Blizzard might release a fix, but if not then this issue will self-resolve once Demon Hunter becomes playable and you get it at level 10.

One of the devs said on Twitter that that the Demon Hunter class will be level 20 as soon as it’s unlocked, so with any luck this issue should be resolvable with the prologue on Thursday, assuming an earlier patch doesn’t take care of it.