Monzo Flex refund issue

I was returning an unwanted purchase in a shop the other day that I paid for on Flex. Opened up Google wallet on my phone, selected Flex card and it said this method isn’t supported. Had to choose another card that was saved in Google wallet to get my refund.

Has anybody come across this? Thinking I might have to physically have the card on me next time?

Thanks

Thanks for the suggestions! I’ll try that and see how I get on. I’ll take my card with me too when I know I need a refund on the Flex account

so never have this issue before, I got a refund back through apple pay when the store didn’t have the item I already paid for they just ask me to tap my card on the machine to get the refund, but do note though it was through apple pay with my flex card