Payment method is set but why do mobile users fail to use that payment method to checkout with a Standard app?
Although the payment methods were checking in Settings page when designing the app. However, when previewing your app as a mobile user, you might get the warning notifications while selecting one of payment methods when checkout.
The causes of the problem here may result from:
Payment method is checked but there is no information to be integrated.
The incompletion of your payment setting on Settings page of the app.
The information is filled in with incorrect information.
Be 100% sure that you set up the payment methods in the right way, please click here for more information with regards to payment settings on Settings page of the app.
Don't tick to choose the payment method that you have neither test account nor live account.
Please contact us via this link if you need any support or questions.