Some tasks in Clarity PPM are not being able to be edited to be set to "Completed" or the % complete is changed to 00% but the status still says "Started" and cannot be edited to "Completed" while other tasks are not facing this issue. 

1. The issue with task status and % Complete not being editable can happen if the % Complete Calculation on the Project is set to Effort and there are any non Labor Resources assigned to the task.
2. Additionally, the issue with task status changes not saving even if the % Complete calculation of the project is set to Manual can be due to there being ETC left on the task. 

Release:
Component: ODPRM

For the % Complete Calculation Method of Effort, non labor resources are not included in the calculations. In order for the task % Complete and Statuses to be able to changed, the project % complete calculation method would need to be Duration or Manual. Note: It is not recommended to change a % Complete Calculation Method of a project once it's been set as this can impact the task data. 

Note: Even if the % Complete Calculation Method of the project is set to Manual, in order to be able to save a task status of Completed, there must be 0 ETCs on the task. See KB000103580 for an error you can see on the Gantt when trying to update a task with ETCs greater than 0. 

Reference % Complete Calculation Method section of the Create Projects, Teams, and Tasks documentation for details on the differences in the three types of % Complete Calculation Methods.

See KB000130549 - Cannot save % complete or other values on some tasks of a project