If you call the tagline the subtitle, you would need to hide the default title and tagline using the Hide options in Main Options > Header > Tite & Tagline section.
Then recreate them manually using the title and tagline shortcode (below) as explained in the Add-Ons page, with the tagline one inside a link, and placed in an insertion area.
[site_title matchtheme=true]
<a href=”pageURL“>[site_tagline matchtheme=true]</a>
Normally you would have placed these shortcodes inside Main options > HEader > Site Title & tagline > Site Logo HTML Box.
BUT it looks like there is a bug, and shortcode placed in there do not work.
@weaver, it looks like if we place a title or tagline shortcode in the Logo HTML box, it does not work, it just displays the code.