That happens in the football threads with some images too.
Serious question: Is there a guide on that? I sometimes get the little blue box with on screen instead of the pic and assume the pic is being blocked. Also, my workplace blocks various sites, sometimes it seems obvious why, and other times, not (no, I'm not looking at porn). I can see if some of the pics show up on threads people are viewing at work, it could be a problem for people. I'll try to keep that in mind, but when images or links are blocked, do ITs get notified? I don't want anyone to get in trouble for pics I post. I don't care for me, because I use a guest login and, like I say, the workplace has a filter so it's not an issue.