Skins not working in game after being selected in the launcher

There has been a problem every time I add a skin in the launcher,select it and then go in game to see my skin hasn’t load in to minecraft Java and im wearing the Alex skin. Once or tiwce i got it to work but,it didn’t in clude the 3D textures on the skin and made the character’s clothing all flat. I dont know why this is happening ever time but mojang please fix it because I really want to use my skins in game.