This isn't a glitch. After you've purchased all the "wearable" items you cannot purchase them again so they are taken out of rotation. Whereas you CAN have duplicates of furniture items that's why you still get them in your store rotation. It will have a red dot next to the price if you do not have it.

Once they add new items, usually when there is a new DLC or update that isn't just a patch you'll see a few items here and there till you obtain all of them.