I can't offer a case where a claim was rejected, but I know of several areas in UK law where having a payment intermediary involved complicates your legal protection.

Lumping the likes of WeChatPay, Alipay, ApplePay, GooglePay, PayPal together, the general concept is if when you use an intermediary

• If there is any concept of a balance being used in whole or part, ie. There is not a direct one to one relationship between the purchase and a transaction on a card statement, this can definitely cause issues legally, and full and part payment can be another dimension.
• If you can't see the original retailer name on the card statement, ie. It says the name of the intermediary rather than the retailer, this also clouds legal protections.

From a UK point of view, its very much the case that you need to be careful where a payment intermediary is used and you depend on some offer or service provided by the card issuer or brand that depends on a certain type of transaction, and if you plan to avail of such things when using an intermediary you need to fully read and understand the wording of the T&C's. This can affect UK Section 75 coverage as explained here but similar principles apply to offers and benefits.

For example expecting an Amex cashback offer on spend in a specific chain of hotel in China if you pay by WeChat or Alipay is unlikely to work.

In the case of the Amex insurance, understanding if payment for a flight or car hire via Amex is necessary to establish the benefit is important, because having an intermediary in the way will no doubt complicate things, especially if on your card statement you can't see the name of the retailer. But if it's the case that the cardholder is covered irrespective of how payment is made and you fulfill other T&C's then there shouldn't be an issue.

It might be very simple, but it can be complicated.