How to restore visual editor in WordPress

I am running WP Multisite in version 4.8

I have a site in the network that lost the visual editor toolbar a ways back (not exactly sure when it disappeared). When you go to Text view mode the content and markup is entirely visible. When you go to Visual view mode the content is there but white text on white background. Plus, the visual editor toolbar is missing all together.

I am running 18 plugins on this site — none of which are TinyMCE, etc.

I have done all of the following:

• I uninstalled every single WordPress plugin in the site to test the visual editor — no success the editor is not present
• I uninstalled the custom WordPress theme and replaced with the WP Twenty Seventeen theme to test the visual editor — no success the editor is not present
• Googled the issue (there are numerous references and posts out there specific to the issue) and tried most all of theme to test the visual editor — no success the editor is not present
• added define('CONCATENATE_SCRIPTS', false); to the beginning of my wp_config.php file to test the visual editor — no success the editor is not present
• Logged into a number of other sites in my WordPress network to test the visual editor — success, the editor is present

Anyone have this same issue?