The issue is caused by a JS error in your theme files: ...wp-content/themes/elision/js/default.min.js?ver=4.7.3
You can see it if you open up the browser console when the slider is missing.
Several of our customers had also faced this issue with Qode themes (Bridge,Elision,etc) recently. Unfortunately the JS error is generated by the theme itself, so we cannot fix it from our end.
Please make sure that you are using the latest version of your theme as they might have already released an update for this with a solution.
Best Regards,Attila | Kreatura Support Team