Thanks! Finally got a chance to play with this again, and that helps a lot.
And because I seem to try all the weird things, I've found there's some odd behavior if you do a Local Node Only search with the hierarchy active. It does not filter to the search results, with either a search box or a custom search. Clicking on the hierarchy explorer shows tracks that aren't in the search results again.
Doing a search of the entire library behaves as expected and filters to what's shown in the search results. (I actually didn't mean to do a Local Node search, but it was set to that by accident. *shrug*)