Example - using advanced search, after entering parameters (such as "titles only", "posts only") you need to scroll way down to the "search" button at the bottom right of the page. Initially that button is not visible when entering parameters; however the default menu bar search button, which uses the same graphic, is visible at the top of the page. That means it is more obvious and simpler to click that upper search button. However, that button only pulls from requests in the field next to it, leading to incorrect results or no results (depending on whether you had left a word typed in there).

If you add a search button at the top of the Advanced Search window (see image) that will help clear up the issue.
If you add a search button at the top of the Advanced Search window (see image) that will help clear up the issue.