Instructor's photo not saved in instructor's account

I'm trying to set my photo in instructor's account but when i clicked save, the photo is not saved.

The photo is well uploaded on the page but when you come back it has disappeared.

I tried several formats (jpg, png), 600x600 with different browsers (Safari, Chrome, Firefox, even on PC). I tried different pictures too.

It seems impossible to save the changes.

Anyone can help me on this?

Thank you.