Unable to print Bing basemaps using the ArcGIS Server 10.6.1 default print service.

Workaround

1. Publish a custom print service from ArcMap to ArcGIS Server 10.6.1. For more information, refer to Tutorial: Publish additional services for printing in ArcMap.
2. Configure Portal for ArcGIS to use the custom print service as the printing utility. For more information, refer to Portal for ArcGIS: Configure utility service.

Steps to Reproduce