Guided Search not working consistently

Hey everyone,

I have a basic site set up using Faceted Search 6.x-1.0-beta2, Bibliography Module 6.x-1.9 and Biblio Facets 6.x-1.x-dev (2009-Dec-18). I've added a handful of Book & Book Chapter typed content for testing.

The Guided Search block is correctly displaying the Biblio fields I've exposed as facets, with appropriate values displayed. However, following some of the links takes me to the "no search results" page. For example, if I click on '1999' for Year Published, I get nothing, but if I do a search for '1999', I get the appropriate results.

So this fails: http://q150dev/fsearch/results/biblio_field%3A0.15%3A%221999%22
But this works: http://q150dev/fsearch/results/1999

This only appears to happen for facets using the 'biblio_field' reference to specify field types; 'biblio/author/' and 'biblio/type/' entries work as expected.