Great plugin for WP, but… it is breaking my menu

As you can see on https://www.jfinformatica.es the plugin is working, it shows the select for a small screen size. The problem is that the submenus are now dissapeared… ??

The development site is https://boogaweb.homeip.net/jfinformatica/ and it is still showing the submenus for ‘Servicios’ and ‘Equipamiento’ but not in production, the only difference is the plugin enabled in production.

Could you help us? We have been trying to sort it out with no luck for some days…

Thanks in advance…

https://www.ads-software.com/extend/plugins/responsive-select-menu/