Cannot add cards to Apple Wallet - App displays Sandbox
I am having problems adding cards to my Apple Wallet. I thought it might be the banks, but I have tried a few different cards with no luck.
A strange behaviour I have is that my Apple Wallet app displays "Sandbox" next to "Wallet", also in the app settings. Does anybody have an idea why this might be? Or how I might be able to remove it?
I do not have a developer account on the phone or anything like that. I have previously used Sandbox functionalities as a developer but not on this account or device.
I am relatively new to iPhone as a personal device (but have done some development). Sorry if this is just normal behavior, but seems odd to me!
iPhone SE, iOS 18