The Find function in gnome-shell works to search for programs and works starting them. If I search for something that does not exist, e.g I write "evloution" instead of "evolution" it won't find anything. This makes sense since there is nothing called this way. When I start a new search now I will not find anything even if i search for something existing like "evolution". The results just stay empty.
So if you get no results after searching once, you will never get results again until you resart gnome-shell