Hi William,
Thank you for writing in, since you’re on a localhost and we can not check the site, please confirm that you are fully updated? (Theme and Plugins)
You can find the latest version numbers here: (http://theme.co/changelog/) Then you can compare them to what’s installed on your site.
If you find anything to be out of date, you can review our update guide.
If you can confirm that, please check the Hide During Breakpoints option of that 4th column, it is more likely that you hide that column in large screen (1200px - 980px) or medium screen (979px - 768px), that is why it is hidden when you have that side panel.
Another issue that can cause that is a malformed HTML markup. Please audit your content there could be an unclosed HTML tag somewhere on your content that messes up the markup on the frontend.
If you can’t find it, you can upload your page template to a sharing site and share it here so we can also take a look on what is happening to that column.
Cheers!