[Plugin: WordPress eCommerce – MarketPress] Items in cart not updating

Hi. My website https://lynnylens.com when you press add to cart and add different items to the cart, lots of times, when you check the cart, nothing is in there, or when there is something in there, it’s just one item, and you have to click update cart for the items to pop up, and also when you click the cart button again, it still shows the one item until you press update cart. and when I try to delete that one item and refresh, it’s still there. Can someone please help me with this?

Thank you.