Audit Trail has been enabled on the Portfolio Plan object, by adding some attributes to be audited in Studio:
Object: Portfolio Plan - Audit Trail Attributes
However, the Audit Trail information is not available on the Portfolio Plan instances.
The Portfolio Plan Default Layout Page does not implement the Audit tab.
The Portfolio Plan is a Subobject of Portfolio. The Audit Trail information for the Portfolio Plan is displayed on its Portfolio Master object.
By default, the Audit Tab is disabled on the Portfolio Default Layout Page until Audit Trail is enabled for the Portfolio (master object).
Release: ESPCLA99000-14.2-Clarity-Extended Support Plus