Why Is Content Entered In Classic Editor Not Displaying on Page?

Shortcodes with hyphens can cause problems and in WP 5, Gutenberg will not accept them, so it is possible this is the issue you are facing. To see if this is the problem, I suggest you install the CF7 Smart-grid extension which replaces the cf7 shortcode with cf7Form, thus removing the hyphens. This will at least strike out this possibility.