The black box usually indicates an invalid file format. Upload a jpeg (.jpg) for best results. Other causes may be that the file you are trying to upload is too large, or too small. The Avatar file size must be larger than 128x128 but there is no need to upload a large image file. Anything over 200± KB is overkill, and files larger than 500± KB may cause the upload to fail. So, resize your image first to reduce file size, save it as a JPEG and give that a try.

Finally, use the alternative upload method if problems persist.