Hi,
Thank you for the details!
I checked the javascript error console for potential causes, and there are at least 20 different errors reported there, please check: https://i.imgur.com/2OCFlS3.png
Usually the cause of these issues is either javascript minification via plugin, or caching them and making them deferred.
First I recommend clearing these issues, it will very likely fix the problem with the elementor saving as well, as they seem to be originated from the same cause.
Another major issue is, that you have two jQuery scripts loaded to the page. That is a big problem, and is probably the main cause of all of the issues reported in the error console.