Skins won't change from Alex/Steve to custom skin

Every time I want to change my skin, it would say that it is activated. However, once I get into the game and check my inventory, my skin is still Alex. I already took a look at the feedback section for skins and it says that it should automatically work for 1.7 and so on. On the other hand, I have 1.16 and yet it is not working. What should I do?