If you get a warning that an IFC file is not published in the federated model, it means that an IFC file has been uploaded to StreamBIM as a file, but that it has not been included and processed as a part of the 3D streamed federated model in StreamBIM. See the article Upload and process IFC.
This can sometimes happen if one forget to add the IFC file 3D-streaming upon upload, or if the person that uploaded the file did not have admin privileges to decide which files should be included in the federated model.