There’s a long list of known issues that, of course, is not posted in the Bug Report forum but somewhere else where you would never expect it.
You ran into two issues both mentioned in that post.
1: A correction to the number of wins from Duels and Arena, pushing you past the 500 win mark for Paladin; and
2: Receiving notification of getting golden versions of cards in the Core set (which you should as reward for achievement), but you cannot yet see those cards because the Core set is not live yet.
The golden cards you unlocked should become visible once the Core set is live.