As the title - Castle has been stuck on Diamonds for 6-7 rounds. It changed a few times when I first acquired it and then got stuck on Diamonds. It seems highly unlikely and perhaps not intended behavior for it to stop changing.
#Castle has not moved off Diamonds for several rounds now
smoky totem
After eight hands on Diamonds, it's now on Spades. Is there some algorithm based on card play or deck composition that influences how it changes, or did I have a truly RNG incident? 1/16,384 odds for it to not change seven times if there's no weight to the roll, but my deck has 20 diamonds compared to 11-13 of the other suits. Even if it's weighted proportionally to deck composition, that's still pretty unlikely. If, however, it's weighted to your card plays, I've played a lot of diamond flushes this game.
In either case, the wording "changes every round" is incorrect if it does not, in fact, change every round.