When I’m on a search results page that has no results (i.e. a page says “Nothing Found”), that page will show a search box in the content area with some text asking the user to try again.
If I then click on the magnifying glass in the menu to search while I’m on that page, the focus goes into the lower search box instead of the one I just opened. So when I start typing my search term, the text doesn’t appear where I’d expect it to.
A suggested solution would be to make sure the focus goes to the upper search box upon clicking on the magnifying glass if there’s a second search box present on the page already.