Cannot add to cart .. stuck in Wait

I’m facing the same issue. But happening in the mobile device, It allows to add one item to the cart thereafter when we try to add another item to the cart it displays “Wait…” and does nothing. Customers are also complaining a lot about the same. Another thing is if we refresh the page and then try to add an item to the cart, it works fine, then we can add as many items. On desktop, once we place an order on the website and then without closing the browser, if we come back to place another other then it shows “wait…” when someone tries to add an item to the cart. Then it does not add even a single item to the cart and the refresh option does not work in this case. Finally, either I need to close the browser or need to clear the cookies to get it to work. But, customers does not understand all this and leave the website. Please help us to fix this issue.