My site’s header/footer and other theme settings were not being displayed so my site was displaying oddly (see below for before/after images).
During troubleshooting I deactivated all plugins and narrowed down the problem to the Cornerstone plugin. When it is activated the site displays incorrectly. If deactivated, it all looks fine. Have you run across this? How do I resolve it? I am stuck.
Broken version = Cornerstone plugin activated
Correct version = Cornerstone plugin deactivated
Cornerstone v3.4.2
X Theme v6.4.2
WordPress 4.9.9 // Note: This was broken with 5.0.1 too