Please also make sure that your machine can communicate through your firewall to the following servers through ports 80 and 443, and that the sites are added to the Trusted Sites list.
1. https://rendering.360.autodesk.com
2. https://api.autodesk.com
3. https://accounts.autodesk.com
4. *.newrelic.com/
When you log in to the portal and Revit, be sure to use the exact same Autodesk ID login.
If the behavior persists, try logging into A360 and rendering from a machine on a different network. If the rendering works as expected, log out, log back into A360 from the original machine and network, and try rendering again.