I hope you are well today and thank you for your question.
I can see you are using the older version of the Jevelin theme on your website so please update it to the below latest version as described here https://support.shufflehound.com/updating-theme/
I can see it just displays for a second and then hides as shown in the attached screenshot.
This can be due to plugin conflict on your site so please try temporarily deactivating all plugins except Unyson, Redux framework and WpBakery page builder plugins and see whether everything works fine and then enable the plugins one by one to see which plugin is conflicting if any.