Error 404 not being monitored

Hello,

Please head over to your WordPress Dashboard > Rank Math > Status & Tools > Database Tools and click the Recreate Missing Database Tables button and see if that works for you: https://rankmath.com/kb/rank-math-status-and-tools/#recreate-missing-database-tools

Please note that some options are only available when you enable the Advanced Mode in Rank Math. If Database Tools is not showing, please switch to the Advanced Mode: https://rankmath.com/kb/switch-from-easy-to-advanced-mode/

In case your theme is using a template for 404 pages, please use the following filter code on your website:

add_filter( 'rank_math/404_monitor/hook', function($hook ){
    return 'template_redirect'; 
});

Here’s how you can add filter/hook to your WordPress site: https://rankmath.com/kb/wordpress-hooks-actions-filters/

Let us know how it goes. Looking forward to helping you.

Thank you.