[Plugin: Collapsing Archives] Filter by taxonomy (post format)?

I am trying to use this plugin to show just one post format of a custom post type. It looks like this would be possible, as “taxonomy type” has a dropdown with “post format” as an option. When I select that and my custom post type, it still shows all posts in that post type, regardless of the post format. What am I missing here? Thanks!

http://ww.wp.xz.cn/extend/plugins/collapsing-archives/