Thanks for writing in! In the latest version of X/Pro, the old X Shortcode insert button were removed because it is already outdated and no longer part of the theme. All the X shortcode features were integrated in Cornerstone. You can still manually insert the shortcode to your page as it will work and based on the classic elements as long as Cornerstone is active. You can also make use of our shortcodes demo as a guide: http://demo.theme.co/integrity-1/shortcodes/
At the moment, there are no plans of adding it back because all of those shortcodes are part of Cornerstone. It would be best that you create the page or post in Cornerstone. In some cases, the manual shortcodes added in the Visual/Text Editor creates issues when viewed on a live page.
Thank you for your understanding.