Hello,
Thank you for reporting the problem.
I could not reproduce the problem when enabling the option on a website using the latest version of Customizr and no plugins activated.
If may be an issue specific to your website. Here is a possible workflow for troubleshooting this issue :

1. Use the latest software versions : make sure WordPress, your theme and plugins are all updated to their latest versions.
2. In your WordPress admin, go to settings > general and verify that your WordPress Address (URL) and Site Address (URL) are identical. The website will not run properly if the urls are different.
3. Cache plugin : if you use a server cache or cache plugin, clear it’s cache content and disable caching via it’s settings.
4. Browser :

• clear your browser’s cache / history,
• try to switch to another browser,
• make sure you do not use any add-ons or extensions in your browser that may conflict with your website.

• Check for plugin conflict : Install the WP official Health check plugin. Activate the troubleshooting mode. Then deactivate all of your plugins. If it fixes the issue, re-activate your plugins one by one, until you identify the plugin in conflict.
• Child theme : activate the parent theme if you use a child theme
• Theme problem : try to activate a WordPress default theme ( Twenty … )
• Javascript : make sure you did not insert custom javascript code ( like analytics, subscription popup… ), for example in a widget, that could break your site.

To log possible code errors on your website, enable WP_DEBUG mode and log the output of the debug.log to a file that you can share on http://pastebin.com/ or https://gist.github.com ( to get a debug log file you need to set define( 'WP_DEBUG', true ); and define( 'WP_DEBUG_LOG', true ); in your wp_config.php file.

If relevant it also helps if you include screenshot(s) of the issue.
(Tip : You can use an online screenshot sharing tool like https://prnt.sc/ to include a link to screenshot.)`