After clicking the "Dressing room" and "edit/create character" buttons, the game shows the owned items, as usual. The issue is when I try to equip an achievement reward.

For example, if I try to put the Diamond Crown in my character (the item is unlocked, I've checked) and select the item, the equip button won't show. The game only allows me to "view achievement" like it would happen if the item was locked.

Screenshoots of the game when I try to equip an achievement reward and when I try to equip a normal item.