Just ran into a rather aggravating issue...
In building a site meant to preview mobile ads, I used the term "banners" in the URL to point to image previews then spent 2+ hours tracking down why it worked in my development environment but not in production.
Luckily a colleague pointed out my ad blocker, which seems to have a broad match on the word "banner"...block all. Changing the name in the path fixed the problem.