When you play Collector's Ire and you have a circus amalgam and for example a pirate and a dragon in hand. The game choses to summon only two cards. Normally you would guess, that it would summon three cards since the amalgam is the one minion type which is missing, which is mech.
I don't know, if the game considerates which minion was drawn first and therefore summons in this order or generates the minion type for the amalgam randomly, but it definitely feels weird.
I could only imagine that the amalgam was summoned after the other minion, so Collector's Ire checks if a minion of the type it wants to summon is already on the board, which would mean that the card summons the minions one by one (wouldn't make much sense, but it's hearthstone's spaghetti code)
Nothing surprising. There are literally hundreds of tiny bugs like these. Nothing game-breaking that would need immediate fixing, but just some minor weird stuff and inconsistencies. Blizzard is currently very busy being silent about the battlepass, theyre waiting for the storm to blow over, so dont expect them to do any balancing or bug fixing anytime soon.