New Email App - Search Functionality Not Working

When I enter search criteria, such as a sender's email name, in the Search box just above the Folder Pane, the search of my Inbox only returns the most very recent instances of the sender's name.  I know there are many more instances it should be finding, because when I clear the search criteria and scroll the mail list downward several pages, I can manually find additional instances by looking through the list myself.  This of course is not an effective process when there are hundreds of pages to be searched on.    

Can someone tell me how to get the Search function of the new email App to search on my entire Inbox?