Thanks for this Ray. I've fought this issue for years and just gave up and had a "help tip" in my search pages to "do an empty search to clear cache" so good to know. I implemented this fix today. Thanks much.
Since the directions are a bit vague, for me, it was a menu on the admin for search. So that menu link added the ?Search=1 to the link. It may not be the same for others, but that is what I needed to know to fix this ongoing issue when clients wanted to keep searching and only got the last results. So thanks much for the solution.