I think I figured out the problem. Since I couldn’t get CAPTCHA to work, I setup a quiz to use as verification. Together, the form does not work, but once I removed the quiz, CAPTCHA now seems to be working.
That fixes the problem. It definitely has something to do with the session save path. It would be nice if eShop supports this as a config option in the future, so I don’t have to modify plugin files.
I am having a similar problem. I moved the installation to another site. I can add items to my cart, but when I hit Proceed to Checkout it redisplays the cart page saying my cart is emtpy. I have de-activated and re-activated, and updated all my settings again, but it doesn’t work. Any suggestions?