im trying to upload pics with iphone 6plus and i get an error message that says
you've uploaded a file with an invalid extension, the image uve uploaded is larger than the maximum file size, or the MIME type of the file uploaded does not match the uploaded files extension. only JPG and PNG extensions are allowed
Assuming that mobile uploads actually work, then I'd say your problem is this:
the image you've uploaded is larger than the maximum file size
I could be wrong though.