I'm running into a strange issue utilizing custom print services in Portal for ArcGIS. Carefully following the online instructions for building a custom print service and feeding it into Portal, it will only allow me to print 2 - 3 services at a time. Attempting to print more than 3 services at a time will return a 403 forbidden error. With 3 services or less active it prints fine utilizing the custom print service. I can use the same print service in a simple Flex map without any issues or service number limitations. The services are secured via standard AD group security, and the AGS server is not federated. Even if I share the map services with everyone on the portal side, and open the services to the public on the AGS server side, I still have the same behavior. Has anyone come across a similar type of issue?