Same here. We are using sitestreams and have a big userbase to add to these sitestreams. Following the best practices, we first create the connection with up to 50 users, and once we receive the control_uri, start adding batches via add_user.json. When adding these batches, we almost always get 404 not found errors, even when, apparently, the first batch of 50 users has been correctly added to the stream (different endpoint, though).
