Skin Disapears after Minecraft Restart

After i have Installed Minecraft new, i wanted to Change my Minecraft Skin. I have done this and Imported it without any Problems in Minecraft. The Storage Setting is set to „External".

 

After i have Restarted Minecraft again, my Skin that i have Set Disapears and it has been Replaced with the Alex Skin from Minecraft. The File „Custom.png" saved in games/com.mojang/minecraftpe is still my New Imported Skin so Minecraft has Saved it to the Internal Storage of my Device. After Checking again if i have still select External in the Minecraft Settings, i am now sure that this is a Bug. The Setting was still set to External.