difficulty searching for messages globally within the program

I feel so incompetent regarding this because I feel it should JUST WORK, but for me it just doesnt... When searching for a name/date/etc in the top right search bar I typically get no result or unusable ones. Obviously this is a problem when I dont know where a particular email may be. When I use the search messages window from my root folder, the one that gives more flexibility ie; match any, subject,contains, etc...i also get no results. For example a message that is currently an open tab in TB cant be found by that search messages window. its still searching and i began the search before I started writing this question... When in a folder or sub-folder, the quick filter search feature works as expected. I've checked all the places i could imagine that might govern global search options that might change this critical seeming lack of functionality and have found none. Is this a true limitation or am I just missing something ? thanks for your consideration- q