latest stripe buy now buttons not working with cached pages

I’m getting the following error with the latest woocommerce stripe plugin (version 4.0.3):

Failed to load resource: the server responded with a status of 403 () /?wc-ajax=wc_stripe_get_cart_details

works completely fine with caching turned off for that particular product page but breaks after the 1st page load on others

its basically preventing the web payments api button from showing on product pages, you can see the purple buy now button work fine here:

https://www.dealtrove.com/shop/diffuser-wrap-bracelet
(this has page excluded from cache)

but if you try another product page it doesnt show and throws the error in the console:

https://www.dealtrove.com/shop/charm-diffuser-necklace

Hope you can help!

Steve