My site is using the Shape5 "Charity" theme on Wordpress 5.6 / PHP 7.3. When you first load the site and hover over one of the navigation links in the header you successfully see the item's menu dropdown display. However after that first navigation link is initiated you cannot view the menu dropdown of any of the other navigation items.

I see this error repeatedly occur whenever hovering over the subsequent menu items:

Uncaught TypeError: Cannot create property 'guid' on boolean 'true'
    at Object.add (jquery.min.js?ver=3.5.1:2)
    at Object.s.event.add (jquery-migrate.min.js?ver=3.3.2:2)
    at HTMLUListElement.<anonymous> (jquery.min.js?ver=3.5.1:2)
    at Function.each (jquery.min.js?ver=3.5.1:2)
    at s.fn.init.each (jquery.min.js?ver=3.5.1:2)
    at ke (jquery.min.js?ver=3.5.1:2)
    at ke (jquery.min.js?ver=3.5.1:2)
    at s.fn.init.on (jquery.min.js?ver=3.5.1:2)
    at s.fn.init.bind (jquery-migrate.min.js?ver=3.3.2:2)
    at t.hideSubMenu (s5_flex_menu-min.js:1)

From other threads it sounds like it might be a problem with my theme's JQuery code and Wordpress 5.6. I've installed the Enable JQuery Migrate Helper plugin (https://wordpress.org/support/plugin/enable-jquery-migrate-helper/) as others have suggested but it did not solve the problem.

I'm out of ideas and have a sad unusable website now. Any help is REALLY appreciated.