FP6 e/os Curve pay

I have a murena FP6 with e/os preinstalled. I installed Curve Pay 5.50.0 from the App Lounge. I have successfully added several credit and debit cards to it. All of the cards work in Google Wallet on a different phone. Curve Pay made ghost withdrawals from the cards when the cards were added.

None of the cards work in tap-to-pay, with the point-of-sale terminal reporting that the cards are incompatible.

If it's important, I'm unable to add Curve Pay as default wallet via the app, though it is selected in phone settings.

Anyone have any idea how to progress?