I use Unity Facebook SDK, a wrapper of js SDK. When I call FB.Canvas.Pay API the js SDK doesn't show Pay Dialog; instead, it returns a callback with the error. Furthermore, this issue doesn't happen in one ENV, however, the client codebase is the same. I assume there might be some settings for imitating such a flow, but I can't find it in the Facebook app dashboard or in the documentation. This error is usually returned when a user closes the popup, but in my case, it does not appear at all.
I checked the app settings in Facebook app dashboard, read the related documentation, but there is no information about this flow