i had the same issue too, but nowadays it seems to be pretty common to change the php settings in the same place you would change the PHP version and that is in the PHP Selector (in cPanel), i did not have any php settings in wp-config.php or .htaccess and i didn’t have a php.ini file, so maybe suggest that to users as well ? it certainly would have helped me.
anyway i tried the fixes you suggested and they didn’t work, so i wrote a long and detailed support topic and before sending it i decided to try it again in case it takes time for some reason and now it works…
Elementor still loads more slowly than with ElementsKit deactivated but at least it works.
Oh and by the way, finding out that ElementsKit was the actual problem was pretty difficult or at least time consuming, because deactivating All in One SEO, All in one WP Migration, Jetpack and iThemes Security plugins also allows Elementor to work again.
Having just one of them active stopped it from working, but if i deactivated ElementsKit instead, then i could have all of those plugins active with no issues.
So clearly ElementsKit is the problem, and while the low memory limit seems to be causing this issue, it also seems to indicate that ElementsKit uses as much php memory as those 4 pretty big plugins combined.
So i think it’s safe to say that some more streamlining of the plugin would be needed.
If i hadn’t made my header and footer in ElementsKit with Elementor then i would have just deleted this plugin, which is what i did on another website last year, where i had the same issue, so this is also a very old and well known issue, that still has not been fixed. Increasing the php memory limit is just a temporary workaround, let’s be honest.