Network Admin Themes Screen on SSL theme updates loads over http

I’m after some info to see if this is just me seeing this problem, or if it’s an issue elsewhere, before I raise a ticket on trac. Here is as much info as I can get;

When viewing /wp-admin/network/themes.php and there is a theme update available, clicking on the ‘View version #.## details’ link pops open the lightbox but it’s blank.

A quick look in the Chrome console says the following;

Mixed Content: The page at ‘https://domain.com/wp-admin/network/themes.php’ was loaded over HTTPS, but requested an insecure resource ‘http://wordpress.org/themes/lovecraft/’. This request has been blocked; the content must be served over HTTPS.

A look into the Network pane in Chrome inspector shows

Request URL:https://wordpress.org/themes/lovecraft?
Provisional headers are shown
Accept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Referer:https://domain.com/wp-admin/network/themes.php
User-Agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.76 Safari/537.36

This is a WP network setup, on subdomains. Never had a mixed content issue before I don’t think. For reference, the network admin (and individual site’s admins) *plugins* pages load properly when clicking on plugin details.

A look at the _site_transient_update_themes option in the database shows;

O:8:"stdClass":4:{s:12:"last_checked";i:1426304375;s:7:"checked";a:7:{s:9:"lovecraft";s:4:"1.11";s:19:"themes/twentyeleven";s:3:"2.0";s:20:"themes/twentyfifteen";s:3:"1.0";s:21:"themes/twentyfourteen";s:3:"1.3";s:16:"themes/twentyten";s:3:"1.8";s:21:"themes/twentythirteen";s:3:"1.4";s:19:"themes/twentytwelve";s:3:"1.6";}s:8:"response";a:1:{s:9:"lovecraft";a:4:{s:5:"theme";s:9:"lovecraft";s:11:"new_version";s:4:"1.12";s:3:"url";s:38:"https://wordpress.org/themes/lovecraft";s:7:"package";s:56:"https://downloads.wordpress.org/theme/lovecraft.1.12.zip";}}s:12:"translations";a:0:{}}

and, if I place a

echo( '<pre>' . print_r( array( $theme_key, $theme, $current, $r ), true ) . '</pre>' );

within wp_theme_update_row(), I get the following;

Array
(
    [0] => lovecraft
    [1] => WP_Theme Object
        (
            [theme_root:WP_Theme:private] => /sites/www.domain.com/production/releases/20150313175000/content/themes
            [headers:WP_Theme:private] => Array
                (
                    [Name] => Lovecraft
                    [ThemeURI] => http://www.andersnoren.se/teman/lovecraft-wordpress-theme/
                    [Description] => Lovecraft is a beautiful two-column theme for bloggers. It features a responsive design, great typography, a full-width header image (which is replaced with the post thumbnail on single posts/pages), custom accent color support, custom logo support, editor style support, a Flickr widget, recent posts and recent comments widgets with thumbnails, and a full-width template. Included translations: Swedish/svenska.
                    [Author] => Anders Norén
                    [AuthorURI] => http://www.andersnoren.se
                    [Version] => 1.11
                    [Template] =>
                    [Status] =>
                    [Tags] => gray, black, red, white, light, two-columns, right-sidebar, responsive-layout, custom-colors, custom-menu, editor-style, featured-image-header, featured-images, flexible-header, full-width-template, post-formats, sticky-post, theme-options, threaded-comments, translation-ready
                    [TextDomain] =>
                    [DomainPath] =>
                )

            [headers_sanitized:WP_Theme:private] => Array
                (
                    [Version] => 1.11
                    [Name] => Lovecraft
                    [Author] => Anders Norén
                    [AuthorURI] => http://www.andersnoren.se
                    [TextDomain] =>
                    [Description] => Lovecraft is a beautiful two-column theme for bloggers. It features a responsive design, great typography, a full-width header image (which is replaced with the post thumbnail on single posts/pages), custom accent color support, custom logo support, editor style support, a Flickr widget, recent posts and recent comments widgets with thumbnails, and a full-width template. Included translations: Swedish/svenska.
                    [ThemeURI] => http://www.andersnoren.se/teman/lovecraft-wordpress-theme/
                )

            [name_translated:WP_Theme:private] =>
            [errors:WP_Theme:private] =>
            [stylesheet:WP_Theme:private] => lovecraft
            [template:WP_Theme:private] => lovecraft
            [parent:WP_Theme:private] =>
            [theme_root_uri:WP_Theme:private] =>
            [textdomain_loaded:WP_Theme:private] =>
            [cache_hash:WP_Theme:private] => 1d1461a47f0ab04c00ea7d4c22cefbf0
            [update] => 1
        )

    [2] => stdClass Object
        (
            [last_checked] => 1426304375
            [checked] => Array
                (
                    [lovecraft] => 1.11
                    [themes/twentyeleven] => 2.0
                    [themes/twentyfifteen] => 1.0
                    [themes/twentyfourteen] => 1.3
                    [themes/twentyten] => 1.8
                    [themes/twentythirteen] => 1.4
                    [themes/twentytwelve] => 1.6
                )

            [response] => Array
                (
                    [lovecraft] => Array
                        (
                            [theme] => lovecraft
                            [new_version] => 1.12
                            [url] => https://wordpress.org/themes/lovecraft
                            [package] => https://downloads.wordpress.org/theme/lovecraft.1.12.zip
                        )

                )

            [translations] => Array
                (
                )

        )

    [3] => Array
        (
            [theme] => lovecraft
            [new_version] => 1.12
            [url] => https://wordpress.org/themes/lovecraft
            [package] => https://downloads.wordpress.org/theme/lovecraft.1.12.zip
        )

)

If you can think of any more info I can provide, let me know.