In Primavera P6 Professional, go to Tools, Reports, Reports and in the Administration & Security report group, run "CV-03 Activity Code Values" if it is available.
If that report is not available, you can create one with the following steps:
1. Go to Tools, Report Wizard.
2. Select Activity Codes subject area. Then from "Additional subject areas", Activity Code Values.
3. At the 'Configure Selected Subject Areas" step, select Activity Codes, Group and Sort then check "Hide if empty" and OK.
4. Continue with the Wizard until you can save the report. Then run it.