SSL, Ubercart, anonymous users cannot add to cart

Set up SSL with this tutorial: http://groups.drupal.org/node/25038

Installed the certs as instructed here: http://www.positivessl.com/ssl-certificate-support/cert_installation/apa...

I'm using Secure Pages to redirect to https and it seems to work fine. I get the lock icon, etc. The only issue I have is that for anonymous users, they get ""There are no products in your shopping cart" when they add a product to the cart. The site is recently migrated and worked fine with this before. I've found a few issues that sound similar: http://www.ubercart.org/forum/bug_reports/13968/cant_add_products_shoppi... and http://www.ubercart.org/forum/support/2569/secure_pagesssl_cart_contents... but none of the suggested solutions worked for me.

I'm posting this here because it seems Aegir's config files are a bit different than the default ones. For example, I don't see the base_url set and I don't see cookie_domain, both solutions suggested in the above issues.

Any help would be greatly appreciated. Thanks!