HCStrike-checkout-client-only

[woeful lagoon]

@fallen epoch clientReferenceId is purely a client-side option. It would never match to an existing customer, so that's just not possible.
If you want to re-use an existing customer in your account you have to create the Checkout Session server-side. See https://stripe.com/docs/payments/accept-a-payment?platform=web&ui=checkout#handling-existing-customers

[fallen epoch]

Ah that's why, I've just gone down the route of creating a checkout session server side and its working now, thanks!