Retailers here just didn't want that Master range in Siege & Earthrise... it was a real struggle for Hasbro Australia to get any retailer to take them, which is why it got a lot more difficult to find that size class last year. (I thought it would have been a perfect size & price point for the grocery stores... but I guess not)
If Hasbro had the same problem in America with their retailers, it might be why Kingdom doesn't have that size class. And if that is actually true (I don't know), it makes you wonder what would have been planned for Kingdom at that price point.