I have trouble getting any results at all ... e.g. if I am on the "General BMW X1" forum and I click on "Search this Forum" at the top right of the page, and type in say "diesel" or "bluetooth" I get an error saying "1. Sorry - no matches. Please try some different terms" ... but I know there are heaps of threads with those subjects.
It makes no difference if I use the "Show Threads" or "Show Posts" options.