Board Thread:Support Requests - Designing Your Wiki/@comment-1994841-20181001150535/@comment-27345308-20181002225255

That's because you're setting your backgrounds to images on insecure,  URLs and your browser is blocking the images as they violate the Content Security Policy (which isn't enforced while you're logged out, because content isn't transferred over HTTPS while logged out).

You should probably upload the images from tinypic to your wiki and link their direct URLs instead.