Out of curiosity, have you tried converting it to another file type like Jpg?
No. I haven't tried that. Hmm. It just does not like this image for some reason.. I'll try that and see if it works
Edit: No. It does not like it even converted into jpg
Second edit: Well that was weird. I cropped the image and then increased the canvas and replaced the area I cropped. I then saved it as a .png and uploaded it and it worked. I'm not certain but I think that the problem might be saving files when the cropping tool is selected. I'll test it out.
third edit: Nope. It still worked. I have no idea what the issue causing this is