VBCS - Cannot Use Service Connections as Data Sources

Summary:

Hello,

I am developing a new appUI extension for our customer's test environment. I can create a service connection and test it successfully, details provided below. However, when I create a new appUI extension and try to use the service connection as data source, new service can be seen on service list but when I expand it shows nothing. So I can't use the service as data source.

Not: For the sake of cross-check, I made similar setup on different customer's simliar instance, and there is not such a problem. Services can be used within VBCS components. Check the user roles and instance migration updates etc.