If your site uses a custom domain, you should also add your site’s custom domain (the domain used to reach the front-end of your site) in the Publish section of the campaign builder.

How do I add an Inline Campaign?
If you’re adding an Inline Campaign, you’ll add either the HTML Placeholder (if using a Sitewide Embed Code) or the entire Campaign Specific Embed Code where you want your campaign to appear on the page.