Mobile menu is always expanded

Have you checked the mobile menu lately? I have installed your theme in a testing website (offline) and I noticed that the mobile menu is not working as expected. In particular, if you add a few sub-menu items, they don’t appear as a drop down list rather than a plain vertical list. I tried every available option, but I couldn’t make it work. Just a list of links, one on top of the other. And, it’s a vanilla install, on WP6.9, with just your theme activated, no extra plugins. To be honest, I consider this a problem with the full site builder, as I have fall into this issues in other themes as well. Either way, I would appreciate it, if you could take a look and let me know if it can be fixed anytime soon.