Why does searching "Any field" turn up fewer records than picking a field?!?

I noticed this behavior for the PMID field in Endnote X4 but now with Endnote X7 it extends to other fields:

if I search for a word in “Any Field”, it finds no records, but if I select “Title” (for example), then it finds the record with that word in the title. This seems crazy - surely Any Field should be a superset of any particular field, no?