"Your upload was not a usable image" even with the right image

I’m trying to upload app icon image with given resolution but still not able to upload the image and getting the error as “Your upload was not a usable image”. Facing the same issue when trying to upload app images as well.

@Bastien_Siebman you’ve had luck with uploading images, right? Any tips here? I know it can be tricky getting it right…

This is a nightmare. I did make it work one day, after hours of struggle. I have the PHP code if needed.