Server Error (404 Not Found) - Wordpress, Elementor

Hello guys, I'm new here, and am not very well versed with cPanel, though I've been working with WordPress and the Elementor plugin for 2 years now. I"m running into this error when I attempt to update/publish a page/post: Server Error (404 Not Found). The error persists even on another site (same webhost) where I have no other plugins installed, and am running the default WordPress Themes. I followed the remedies given by Elementor and have not yet found a solution, nor been helped by them. I am thinking this could be resolved somewhere in the site's cPanel area. In the browser's Developer sub-menu, using the Network tab, the 404 error is indicated to be tied to the admin-ajax.php file, can be seen in the image attached. I kindly request some help. What should I do? So far, I have tried the WordPress based fixes, but none has worked. Is this error correctable from the cPanel end? If so, what should I do? Thanks in advance.