Similar problem, but it’s erratic.
I can get some images to show up. Others don’t.
I can’t figure out why some don’t. I’m using jpg format for all of them. I experiment with various pixel sizes but that doesn’t seem to change anything. I delete and re-upload an offending image, and it still doesn’t work. I upload an entirely new, different image and it appears just fine.
It seems that wordpress is blocking specific images, and I can’t find the pattern.
My workaround: pick a different image until I find one that shows as I expect.
Not very satisfying, but there it is.
http://www.jerschmidt.com
