Hey all, and sorry for the confusion.
We currently have a restriction on new accounts playing Season of Discovery, similar to the purchase of WoW tokens.
This means that if this is your first time adding game time on your WoW account (and if the game time was added recently), you will not be able to trade with other players, use the auction house or in-game mails.
Once this period of 30 days has ended, the restrictions will be lifted automatically. If you’re still seeing restrictions after that however, you will need to log out of your account for at least 12 hours.
Hope this clear things up. 
Edit: Thank you to the players who reported seeing the restrictions after following the above instructions. This has been forwarded to our developers.