Ingame it doesn't display any message that it is saving, generating, or leaving. Usually the only thing that happens after you try to upload skin is that it brings you back to title and shows loading screen as if you would have been just started the game.
The only message that it is saving image is from the photos app.
I tried to import skin while on server but this time it displayed this message and send me back to title screen. I attached screenshot in attachments.
This bug just happened too on Windows 10 today. Yesterday everything seemed to work just fine.
Hello looks like this new update fixed this issue (at least in my case). Now you can import skin like before without any issues.