How many ways are there to mess up the complex functionality of a piece of software like Elementor? LOTS!
The most annoying outcome of a malfunction is having Elementor stuck on its "Loading" Screen.
The makers of Elementor have addressed that subject (somewhat) in this article: https://elementor.com/help/elementor-not-loading/
But they left out two big glaring 'quick fixes'.
Fix 1
"Reinstall" WordPress. It's been made fairly easy by the WordPress people and can also be done manually (not covered here).
- Dashboard, Updates, Re-install version XYZ Button
It works 99% of the time. And when it doesn't, about half a percent of that time, just try it again and it works the second time. The last .5 amount where it doesn't work is probably the reason why Elementor won't work.
The reason this is such a glaring omission on Elementor's "How to fix issues with Elementor" knowledge base is because Elementor depends (AKA dependencies) on a great number of items in WordPress. Some of those items are fairly obscure. If the items in question have been changed, moved, altered, or even deleted, they can cause some really frustrating issues with Elementor that lead down all sorts of solutions paths that don't help.
Fix 2
Fix 2 really isn't a 'fix'. It's most likely an 'un-configuration'. There are many plugins that offer performance and security improvements with most doing a decent job. One 'performance and security enhancement' area that is a bit dangerous to wander into, in regards to Elementor, is the WordPress 'Heart Beat' functionality. If the Heart Beat functionality is turned off, Elementor won't work.
- If any 'performance' plugins have been installed, look for anything that refers to Heart Beat and 'turn it back on'
Fix 3
Permissions and Ownership. And in this case, permissions and ownership refers to the web server that's hosting a WordPress site. This might be a subject that's outside the realm, understanding, purview, etc. of many web site developers. But just because one doesn't understand how a toilet works or how to grow food, doesn't diminish the importance of such things. And on a side note, all of the non-wordpress stuff is worth learning about too. Anyway, permissions can cause issues in regards to how a WordPress site functions (or doesn't), beyond Elementor. Elementor may be installed and configured perfectly, but if the foundation it is standing on isn't working properly, one can't expect Elementor to work properly either.
Below are the commands to set the proper permissions for the WordPress Directories and Files on a web server (this example uses Apache, NGINX, and other chown commands are similar);
chown -R apache:apache DirectoryName
find FolderName -type d -exec chmod 755 {} \;
find FolderName -type f -exec chmod 644 {} \;