Hi,
The TaskPercentCompleted is related to the duration so it can be populated evenif the task has no resource assigned, so no work.
The TaskPercentWorkCompleted
will be related to the work of work done and not the duration completed on the task. So a resource must be assigned on the task with some actual work to have the TaskPercentWorkCompleted.
Hope this helps,
Guillaume Rouyre, MBA, MVP, P-Seller