Custom HTML not working

Hey guys, I’m pretty frustrated right now, so hopefully someone here can tell me what the issue is.

So basically, on the blog section of my site, I’ve been trying to insert some customer HTML (an affiliate banner ad). I know the code is correct because I tried putting it in in an html editor and it showed up (after I disabled adblocker).

But on my blog, when I try to add custom html, and click preview, it’s always blank. And at first I thought maybe the preview just wasn’t showing for some reason, but even after I save and look at the page, there is nothing there.

Why is my correct HTML code not working on the custom html block on my blog?