The same thing happend to me. Here's more information I have found.
At first,I uploaded a skin file named A.png, and then there is the glitch. I tried to upload another skin file named B.png, but it did not work. However, if I make changes on A.png and upload it, its changed textures can be displayed, but the model still incorrect.
So, there is a problem that you can cover the file you uploaded before, but you cant upload a new skin file.
Brand
The same thing happend to me. Here's more information I have found.
At first,I uploaded a skin file named A.png, and then there is the glitch. I tried to upload another skin file named B.png, but it did not work. However, if I make changes on A.png and upload it, its changed textures can be displayed, but the model still incorrect.
So, there is a problem that you can cover the file you uploaded before, but you cant upload a new skin file.