Hey @Martin Fenge!

Since the stores and banks handle this security step, RevenueCat doesn’t have any insight to what might be happening here. It sounds like the bank website is failing.
 

What should we do about that? Did we miss something in our payment implementation or should we configure something more on RevenueCat as well?

There’s no extra configuration on RevenueCat for this type of purchase- sounds like this issue is coming from the bank.
 

Also, is there a possibility to have multiple web-hook urls? Basically we would like to have one url for the Sandbox account for the development environment and a second url for the production environment. Can this be done?

We don’t currently support more than one webhook URL. Typically we recommend that users set up a neutral webhook URL that can differentiate between the types of events based on the `environment` property of the webhooks: https://docs.revenuecat.com/docs/webhooks#events-format
 

And lastly, can we somehow test this flow (paying with a card with NemID verification) on the test versions of the app and RevenueCat sandbox account. (Otherwise the only way to test this, would be going live with the app, and we obviously don’t want to test the app in a live environment).

This is similar to Ask to Buy payments, or interrupted purchases. You can enable interrupted purchases for sandbox accounts in the Users section of App Store Connect:

For more about the secure payment flow, I’d recommend reading our blog post: https://www.revenuecat.com/blog/strong-customer-authentication