Smart Group for each search term - so why so many 'Unfiled' entries?

Oh, I think I see what you’re saying now. That would make sense.

I’m generally searching ‘Any field’ when I look up a library catalogue on the online search. The smart groups are also configured to look for ‘any field’ and find the same search term. I’m not sure which fields are not being transferred over, and why. Is there a way to modify this? And if so, will it retroactively add the fields, or only make it work from here on?

Thanks