This is how I fixed it:
When you get one of the upload dialog boxes, there may be a check box next to the UPLOAD IMAGE option at the bottom. It is one of those "I agree to something xxx" that you have to check. Once I checked it, the UPLOAD IMAGE button became activated.
My mother would call that a "snake", as in
If it was a snake, it would have bitten you already.
In this case, it would simply bite you once, then quickly crawl away.
This is what you will usually see. Except for one time.
Look carefully, to the right of the "Upload Image" button! Do you see it? Take a good look right now - after you check the box and upload, you'll not see it again.
Probably most folks see it once, check the box, upload, and they never see it again. Check TOS boxes isn't all that earthshaking, and very few folks ever read the Terms. So later, when your friend asks you why his upload doesn't work, are you going to think of it? I doubt that I would.
But, thanks to tgold, we might.