I keep having this huge problem on one of my self-hosted WordPress website. I use Elementor plugin for adding dynamic content and widget. I also have the WordPress WP Super Cache plugin installed to speed up the page load time.
However, I just can't seem to make Elementor work without deactivating WP Super Cache plugin. So there must be some conflict between the two plugins. And I compare the plugin setting on two of my sites running the same plugins, I found the problem.
Whenever I add a new page or post, it doesn't let me edit the content with Elementor page builder. It keeps redirecting the page to 404 page not found error page with the URL like this. http://mydomain.com/?p=123&elementor.
There is a setting in the WP Super Cache that you need to disable. I did not remember how it gets set that way, but it works like a charm after I disable the checkbox that says.
"Make known users anonymous so they’re served supercached static files."
Once you uncheck the box and save the settings. Elementor works like a charm. See the screenshot below.