adding to cart not working anymore

Hello,

So the plugin was working wonderfully for months. I am really not sure what happened in the past couple weeks, maybe a wordpress or woocommerce update broke the functionality. but when a customer is browsing by category and start to add items to the cart, different error messages shows up like ‘security check failed’ and ‘cart item not found’. sometimes the item is added in cart but when the customer goes to the cart or checkout page the item would be gone.

I thought the problem is with caching, but I have disabled object cache pro and Cloudflare caching and the problem presists. Only if i disable the flying pages plugin the problem goes away and all customers would be able to add to cart without problems.