Drop-down menus off main theme menu don’t appear when plugin active

When the Shortcode Maker Version 4.0.8 plugin is active and I click on a main menu item in my client’s site (using a customized version of the Sage theme), I’m supposed to see a drop-down menu appear, but it doesn’t. If I deactivate the plugin and do nothing else (other than refresh the page), then the drop-down menu will appear as expected. So it appears that something in the Shortcode Maker Version 4.0.8 plugin is affecting our menu code / JavaScript. So while the plugin looks promising, this makes it unusable for us right now.

FYI: The client site URL with an example of the menu (but with the Shortcode Maker Version 4.0.8 plugin DISABLED) is at https://hsgadvisors.com.