Nav bar and hamburger bar appear together starting from tablet view

I have a problem with my navigation. I recently purchased a Webflow template, and I am editing the navigation and trying to make it responsive, I notice once I click on template both hamburger menu and normal menu appear and when the hamburger menu is clicked nothing happens. I have noticed also It’s impossible to add any new navigation item next to “portfolio” without ruining it

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Webflow - Mariyam's UX Site

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You probably have made unintended changes on your template. But navigation on Webflow has a certain layout to maintain.

Your links should be within Nav Menu block. You can also see that when you click on add new link on menu settings.