Sorry to have to raise another issue with you, but I noticed that sub menu items are not appearing in my main mobile menu when I am in Flexbox mode. If I switch to Floats, they reappear and work normally.
The main menu item expands to display the area where the sub-menu items should appear, and the SVG arrow icons also display, but no text to click on. The site is in full AMP mode.
I appreciate that this is probably the gods telling me that submenus on mobile are a bad idea . . .