The title says it all. I have the correct setting for the menu in admin: Locations –
Main & Slideout.
I have the correct setting for the menu in Customize/Menus/Main Menu:
Slideout Navigation (Current: Main Menu)
Primary Menu (Current: Main Menu)
Works fine on phone. On tablet, the menu opens up with no links
Note: I set the content of the page header to be visible on a tablet in order to have a working menu.
I think first you need to decide whether you want to use GP or Elementor for the menu and stick with one only across all platforms.
GP’s menu should show up by default. You might need to disable the nav menu for Elementor.
Looking at your current layout, I think it might be easier for you to use Elementor for desktop, tablet and mobile. If that’s the case then might be best to check with their support to see how to implement it for all devices.