The included ArcGIS Pro Advanced license in the GIS Professional Advanced user type cannot be consumed by ArcGIS Pro in Portal for ArcGIS 10.8.

Workaround

1. Generate a working Portal for ArcGIS 10.8 license containing the following items:
   1. x10 Creator
   2. x50 Viewer
   3. x10 GIS Professional Advanced
   4. x5 ArcGIS Pro Advanced
2. Import this license to Portal for ArcGIS 10.8 and ArcGIS License Manager 2020.0, and configure the appropriate hostname and port.
3. Apply the GIS Professional Advanced license to a built-in user.
4. Configure the ArcGIS Pro 2.5.1 licensing portal to the Portal for ArcGIS instance.
5. Attempt to consume a license and log in to Portal for ArcGIS with the built-in user.
6. ArcGIS Pro consumes the license and the Pro home screen launches. It appears that any add-on Pro licenses in the environment are consumed in place of the defective Pro license in the GIS Professional Advanced user type.

This was observed in the customer's AWS environment and reproduced in an on-premise environment.

Steps to Reproduce