The Search Box Gadget in my Blogger blog does not work reliable. Some search terms show results others not, though the search terms are present in my blog.
Using the Blogger navbar searches the blog as well and produces correct search results.
It seems the Search Box Gadget has a bug.
I found a solution from 2009 that still works around this problem.
So the real question is, is it a bug or a feature? And if it's a bug, why does it take Google so long to fix it?