MCPE skin bug

I used a certain skin in MCPE from an app called SkinSeed and now none of the skins that I import and try to use in the game are working. I click on owned, import, click on the skin that I want to use, and then when it goes to ask me whether I want to use the slim armed or classic version, nothing is there. Now whenever I try to use one of my imported skins and go into a world, it says invalid or corrupt skin.