You must have tried to paste that in as opposed to actually uploading it? Not showing up.
Normally you have to go to desktop mode in Facebook, full size, open image in new tab, get the actual address of the photo itself, to post the thing. It's been getting harder and harder to do it.I tried to link the picture which actually is loaded (and "public") on my FB page but don't know what happened (I did the task from my err smartphone...).
Post pre-view was not showing the picture, and when I hit "post message" well that is the result...