Mobile Menu disappears when Homepage linked to a Page, not the Posts Page

I use a Highend theme version 3.6.2. It is the latest update as it is stated on the Highend theme page.

I use the theme mainly as an official blog of our entity. I already created main menu and mobile menu. Both menu items refer to our main website pages that do not use the highend theme.

Everything worked fine. The mobile menu appeared on the mobile phone and Ipad perfectly. My homepage ( as it appears in the highend options) was NOT linked with a static page when the mobile menu was working fine.When I linked the homepage to a static page, the mobile menue disappeared.

I tried to solve the problem, but I could not. I do appreciate your help. We need to link the homepage to a static page and we want to have the mobile menu appear as usual. Please help.