I’m currently running the latest version of the Royal theme (1.4) on WP 4.0.
When I select a page in the header nav (Ex. Contact), the page will load correctly and highlight the page that is currently active (Contact). However, when I scroll down on the page, the “active” page seems to change and the incorrect link is highlighted in the header nav.
This issue isn’t limited to my site; you can recreate this issue on the Royal theme demo page. Navigate here and click “Shortcodes” in the header nav. The page will load and the Shortcodes link will be highlighted. Now try scrolling down and notice that the “Demo” nav link becomes highlighted.
I’m unsure if this issue was in previous versions of the theme.