There's an issue with Samsung Wallet, that was present in Samsung Pay that I've banging my head with.
I've just downloaded Samsung Wallet onto a device. Select "Add" > "Loyalty Cards" then "Import Loyalty Cards" In my case there are three cards to import. Import them fine. Delete one of the cards. Click "+" then "Import Loyalty Cards". The card can be reselected and downloaded again.
How the hell do you delete the these cards from the cloud?