I'm using SEO v1.2.5
in Dashboard/Settings/General, my WordPress URL and Site URL are different.
SEO is using get_site_url() and assigning the resultant link to the root Home link in the breadcrumb trail. unfortunately, it's the wrong url. (/wordpress-seo/frontend/class-breadcrumbs.php line 73)
according to WP's page here;
The 'Home' setting is the address you want people to type in their browser to reach your WordPress blog
between this description and the labels in Settings/General, one could be forgiven for getting very confused, but it would appear that get_site_url() is not the ideal function to use to get the Home url of the site.
could you change this? to perhaps get_option('home') ?