Important: You should backup your site before following these steps!
Deactivate all plugins that aren't required in order for the problem to be visible. If you're using a page builder, this means you should leave the page builder active and deactivate all other plugins.
Since something is still broken, you should leave your site in its current state and continue troubleshooting to identify the problem.
You can now close this window.
The problem was caused by a plugin or theme conflict.
You can now reactivate the deactivated plugins or themes one at a time. After each activation, check for the problem again. Once you see the problem return, you'll know which plugin or theme is responsible for the conflict!