Upgrade to 3.5 – CSS not loading on login page(HTTPS problem)

I’ve just upgraded to version 3.5 on https://www.cogmotive.com/blog

I did a manual upgrade and it all worked fine, it even updated my database for me.

However, I can now not log in. Also, my login page does not have any CSS applied.

Chrome shows the following error:

[blocked] The page at https://www.cogmotive.com/blog/wp-login.php?redirect_to=http%253A%252F%252Fwww.cogmotive.com%252Fblog%252Fwp-admin%252F&reauth=1 ran insecure content from https://www.cogmotive.com/blog/wp-admin/css/wp-admin.min.css?ver=3.5.
[blocked] The page at https://www.cogmotive.com/blog/wp-login.php?redirect_to=http%253A%252F%252Fwww.cogmotive.com%252Fblog%252Fwp-admin%252F&reauth=1 ran insecure content from https://www.cogmotive.com/blog/wp-includes/css/buttons.min.css?ver=3.5.
[blocked] The page at https://www.cogmotive.com/blog/wp-login.php?redirect_to=http%253A%252F%252Fwww.cogmotive.com%252Fblog%252Fwp-admin%252F&reauth=1 ran insecure content from https://www.cogmotive.com/blog/wp-admin/css/colors-fresh.min.css?ver=3.5.

Indeed, if I look at the login page source it is trying to load the CSS using HTTP rather than HTTPS.

I’ve confirmed that my siteurl and home values are using https in the URL.
I’ve disabled all plugins, no difference.
This was working fine in the previous version.

Any ideas I can try?