Hi there,
I have just checked and the sub menu items for the Integrity 1 demo are displaying on mouse hover without need to be clicked. See screencast below:

Perhaps you are talking about the mobile menu? If so, by default the submenu items will be displayed as you tap on the main menu item.
In case you are seeing this issue on your site, where you need to click the menu item on desktop for the sub menu to be displayed, kindly try first to clear your browser cache. If it does not change anything, try testing for plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
If the issue persists, please provide us with the URL of your site so that we can check it further and kindly provide us with the admin access to your site if you have an under construction page active. Kindly place the logins in a Secure Note which is the key icon under your replies.
Thank you.