I hope you are well today and thank you for your question.
Could you please share with me the screenshot of the body mega menu item that you have configured?
Also, would you mind if I log in to your site and do some troubleshooting? If this is ok then could you please temporary share me your site admin login details privately by adding them in the box having text “Enter your private content here (only you and forum moderators will be able see it)”?