This seems to be a backend issue with the private profile settings. No further details however, talking to several layout creators about this issue as well.
Edit: Update from twitter, image issues should be fixed. Any further issues, report to the support email asap.
Just posted a blog post with an image. The image shows up when editing, but after publishing it is broken. It's not using the URL of the image but instead prefixing the URL with some SpaceHey URL.
EDIT: Just realized this is a problem with Imgur as it redirects the direct link to the image with a 302 redirect.
I was having that problem too. Like some people are saying, I believe Imgur is the problem here. I happen to be using Imgur when my problems started occurring. There is an Imgur alternative that is working perfectly for me. It's called Catbox. I'm hoping that'll help you out. :)