In the Classic UX timesheet page to add tasks into the timesheet, navigating to another page or sorting by column shows an error:
You are unable to add tasks if it involves moving to the next page. It throws the above permissions error.
Steps to Reproduce
This issue is fixed in Clarity PPM 15.6 patch 1 (15.6.0.1) and in 15.6.1 (15.6 SP1).
Workaround:
Filter by the task name, project name or other criteria to narrow down to the task to add it to the timesheet.
Similar scenario (fixed in 15.7.1):
Similar scenario (being analyzed by Engineering)
Error 401 - Unauthorized using Add and Select More button in Classic timesheets