Yeah I think that’s an improvement that can be made to the UX — to ask to add the mint in the payment request if you don’t already have it added. 

Since that one was made in @boardwalk, the mint is https://stablenut.umint.cash/

Here’s a payment request from cashu.me if you want to try again. I’m pretty sure the mint is Minibits. 

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 

 I think it should be automatically added as part of the transaction process if that mint isn't in your configured mint list, just like if someone sends you a an ecash token, the mint its from gets automatically added to your wallet if it's not already present. There shouldn't be manual action required.