I played a game tonight with Order of Astrologers, and I had an issue where it appears to be topdecking and then shuffling and then drawing, resulting in me not drawing all the cards I just topdecked.
Unfortunately, this game gives an "internal error" when loaded, so I can't look at what happened. You will only draw the 5 cards you topdecked if you had no card left in your deck. If there ware still some cards, then you will (at that point in time) draw them and only the remaining ones come from the topdecked cards.
But the fact that the game can't be loaded is a hint that something may have happeneed that isn't right. I'll test some things and see if I get similar problems.