As others have already stated, the monthly collection items are a situation where you pick one item, and you can choose from the items in that particular collection. These collection have never given out all of the items, and when you go to open the collection, it will tell you "Lucky you! You get to choose a specific item from these choices"

Once you click on an item, that's the item you receive from the collection. I'm going to close this up since there's no problem with the item itself and there's no bugs involved.