Actually, I just had a look in our issue tracker, and I have another (more detailed) update for you.
We have a hotfix going out to the server for this on Monday which will actually fix the amount of gold generated, so that players receive the correct amount for 4-star kingdoms
There will still be a display issue in the game, and it will still SHOW the incorrect value in the kingdom menu. This will remain in place until we do another update for the client.