Add to cart is not working in Multisite Main Site with ssl

Add to cart is not working in Multisite Main Site with ssl. Marketpress is not network activated.
I have tried to this fix though the issue is on the main site not on a mapped domain. https://premium.wpmudev.org/forums/topic/add-to-cart-is-showing-mixed-content-error-on-mapped-site#post-1304929
But that does not help.