When typing a location in the map's search field, the user is unable to see the text being typed because of a white rectangular box that appears. The text becomes visible only upon pressing 'Enter.'
The following images show how the text field appears prior to a search (Image 1), while typing a location (Image 2), and after hitting 'Enter' or the search button (Image 3).
This is most likely caused by a z-order of another element on the page which is lower than the map but higher than the search box.
You may contact the person who has customized the site and theme to perform adjustments. Alternatively, if you require a low-tech resolution, trying a different theme may help fix it.