Xstore Proceed to checkout button missing

Hi,
I’ve had numerous complaints from a client this week about people being unable to proceed to the checkout from the shopping cart page as the button that normally appears below the basket totals has disappeared.
This problem has only become evident since the last WP update (5.5). I’ve tried all the usual stuff like de-activating plug-ins etc but can’t fix it.
Two things to note are that if the customer has already visited the checkout page and entered an address then the button does appear, Secondly, Woo is stating that some of the templates (including the cart one) are not up to date but I don’t want to touch these unless it breaks anything.
Any help would be greatly appreciated.