It’s as I guessed, you have a JavaScript error on your home page…
That JavaScript error is most likely the cause of your problem, and it is not being caused by the Vellum theme. JavaScript errors are most often (almost always) caused by plugin conflicts, so to begin troubleshooting this issue you should deactivate all plugins (all at the same time) except those required and recommended by the theme to make sure the additional plugins you have installed are not causing any issues. If the problem goes away, reactivate your additional plugins one at a time (individually, not incrementally) until you find the one responsible and let us know.
If the problem persists after all additional plugins are deactivated (all at the same time), please leave them all deactivated, let us know and we will work from there. In case you are in any doubt, these are the four required and recommended plugins that you can leave activated while you troubleshoot your problem…
– CSS3 Responsive Web Pricing Tables Grids
– Go – Responsive Pricing & Compare Tables
– Slider Revolution
– WPBakery Page Builder (formerly WPBakery Visual Composer)
So if the problem persists with just those four plugins activated, please leave all other plugins deactivated, let us know and we will work from there. Thanks.