Yes there is a manual fix " /run PVPQueueFrameCategoryButton2:SetEnabled(true)"
But lets all log a bug report, and make a statement…
If PVE was affected, it was already fixed 3 days ago, before it even occurred.
Go to: Menu → Support → BUG Report.
" When trying to queue for Arena, I get a message saying I’m not max level, but I am. Relogging, resetting UI, and disabling addons didn’t help. This issue is ruining my WoW experience! "
Will give it a try this evening, thanks for the /command thingy, will give it a shot, however bit odd that there’s zero response on blizzards end, oh well.