The Athena Pro primary navigation features white text, sitting on a grey overlay on the Frontpage, and a black bar in Pages and Posts.

The menu supports a defined number of characters, plus a logo. If the number of characters in the menu plus the width of the logo exceed the horizontal length of the menu, the text of the menu is bumped down, appearing in a line below the menu. If the site pages are white, then the white text is not visible.

Simply resolve this issue by reducing the character count in the primary menu. For example:

Shorten menu items. Eg. Change “Schedule of Events” to “Schedule” or “Events”
Group related pages together under as submenus. For example put “Contact” and or “Our History” under “About Us”.