Menu defect (passiv) on iPhone/mobile

Created a simple menu with 10 linked menu items (linking to non-WordPress part of my site), 2 page menu items and a language selection menu item (DK/US) with Polylang - but the menu is passive on Safari on iPhone iOS 10.3.3 (nothing happens when pushed). Works in Windows based Firefox & Chrome plus on iPad Safari, but not on iPhone... Shifted theme to Black Light and deactivated GP Premium and the menu works... Shifted back to the GeneratePress theme and re-activated the GP Premium plug-in and the memu failed again on iPhone.

Regret buying GP Premium.