Is there a call that I can use from the REST API to get all of the users that have subscribed to a particular Blog?
Yes using this: community.telligent.com/.../application-subscriptions-rest-endpoints
When using this endpoint, we are only getting data back for the current user.
Is this the expected behavior, or do you have any recommendations for the payload to allow all subscribed users to be returned?
This does seem to be the behavior for that endpoint. There is a supported in-process public API for listing subscribed users, but it is unfortunately not also wrapped with either a REST API nor widget API extension.
The in-process API for listing subscribed users is:
var api = Telligent.Evolution.Extensibility.Apis.Get<Telligent.Evolution.Extensibility.Api.Version1.IApplicationSubscriptions>();
var users = api.SubscribedUsers(Guid applicationId, ApplicationSubscriberListOptions options = null);
I am logging the lack of REST and widget APIs for this as a bug. In the meantime, you could add your own REST endpoint plugin to wrap the supported in-process API.