Custom Fields not showing on edit page. When I look at Screen Options it doesn't even show up.

I've looked around for a while and saw that people who had the Advanced Custom Fields ran into the same issue. However, I do not have that plugin installed and I haven't found any other help online.

Solution: The Karma theme removes the custom fields meta box in the file Karma/framework/site-options-functions.php. If you go to Appearance -> Site Options you'll be able to show the hidden meta boxes.