MarketPress not working with SSL

After I added SSL to my subsite, the Add to Cart button doesn’t work, only spins …

https://monosnap.com/file/bD4bYNM6h0fejrVgf0iO62ca8mJfbm

admin-ajax.php get blocked loading mixed active content. I am using Cloudflare for the SSL as well as a Wildcard SSL on my server. Please help.