Found something strange... so it appears that when I drag the first search up to the search bar, the criteria is mangled: instead of showing up as Event Name = UserLogon (for example) it looks like this:
So the question is, why is LEM mangling the search criteria? I'm not modifying it at all, just dragging it up from the Refine Fields column.
I think in the first search case when you drag over from the refine fields into the default empty text search, for some reason it's not replacing it, it's dumping what you see into it. Instead, I think if you empty out the default empty box search (hit the X when you hover), THEN drag up your refine field, it might work. It's kind of irritating and something we should fix.