I have no clue.
I said, until I asked DH, the resident computer whiz, how come some posts show pic's and others only red x's. He said I should right-click on the x, which brings up a drop-down menu - at the bottom is "properties," which he said to click on. That brought up a window that included, among other stuff, the URL of the picture. Copied & pasted that URL into the address box at the top of the screen, and the picture appeared. Hit "Back" and - presto - the picture now shows up in the post as well.
It's all smoke & mirrors as far as I'm concerned, but hey, if it works - try it! :)
P.S. It works for a while. After a few moves back & forth, it no longer shows. But at least you might get a look at it with the copy & paste of the URL.