Why is the Debut mobile navigation not functioning?

Technical Q&A
1

Hello! I recently found that the Debut mobile navigation on a store I help manage has stopped working: https://kitchendetailprintshop.com/

In the console, I’m getting this error:

Uncaught DOMException: Failed to execute 'querySelector' on 'Document': '.mobile-nav__dropdown[data-parent="
                about
                -1
              "]' is not a valid selector.
    at goToSubnav (http://127.0.0.1:9292/assets/theme.js?v=16203573537316399521667812850:3204:18)
    at HTMLButtonElement.toggleSubNav (http://127.0.0.1:9292/assets/theme.js?v=16203573537316399521667812850:3199:5)

Does anyone have any suggestions as to why this is happening before I start trying to rebuild the mobile nav from scratch?

Thank you for your time!