Q: Apple Pay - American Express (AMEX)

I have been using Apple Pay on my Apple Watch in the UK since launch with American Express and Nationwide.

Over the last month I have had a problem specifically with American Express in Boots. The watch shows a tick implying the payment is accepted but the quick pay machine states that payment is rejected. It works ok with nationwide.

Is there a know problem with American Express?

Is there a resolutions?

Has my card been charged (I think not)?

Thanks,

Matthew