Express Checkout buttons not showing at the Checkout (but they are enabled and show in the cart)

I’ve not managed to find this exact issue anywhere so I’m asking the question.

We have express checkout options enabled (Paypal, Shop Pay, Apple Pay, Google Pay).

The relevant buttons show in the Cart below the ‘check out’ button, but they do not show at the Checkout where I’d normally see them.

This is a new theme but I was under the impression the theme cannot affect the checkout.

Shopify support implied that because they show in the cart, they won’t show in the checkout? Does anyone know if this is the case?

Any ideas anyone?

Thanks

Dave