Here are some reasons why a web object could be missing from your published Storyline course.
You're Viewing the Published Content Locally
Be sure to upload your published course to a web server or LMS for proper viewing. Otherwise, local security restrictions in your computer and browser can cause various features to fail.
The Hosting Website Isn't Secure
Modern web browsers have changed the way they handle mixed content, such as iframes. As a result, web objects may not work in the latest versions of web browsers, such as Internet Explorer, Google Chrome, and Firefox. Web objects may flicker or be missing altogether. The solution is to host the content on a secure website and use
https:// for your web object.
The Hosting Website Doesn't Allow Viewing in an iFrame
If your web object still won't display, the hosting website probably has its X-Frame-Options set to SAMEORIGIN or DENY. This means it can't be viewed in an iframe, such as a web object in Storyline. A common example of a website that won't work as an embedded web object is Facebook.
You can still use a website that doesn't support iframes in your Storyline course. Just set the web object to display in a new browser window.