Can't override default values from template when use_last_segment is used

[tyssen]

Working on an EE 2.11.9 site with SEO Lite 1.4.9.3 I have this in my global template embedded with Stash:

{exp:seo_lite
  use_last_segment="yes"
  title_postfix="{stash:_postfix}"
  default_title="{stash:_page_title}"
  default_keywords="{stash:_keywords}"
  default_description="{stash:_meta_desc}"
}

and this in the template that embeds it:

{stash:embed
  name="layouts:global"
  stash:_postfix="test"
  stash:_meta_desc="test"
  stash:_page_title="test"
  stash:_keywords="test"
}

With use_last_segment I get the entry title in the title tag but the default module values for description and keywords. If I take use_last_segment out, then I get test which is what I'd hope I'd get using use_last_segment if there's no values entered for that particular entry in those fields.