We have tasks with assignments and no effort. In Organizer we set the task status to 'Completed' and % Complete changes to 100%..
When we run the Update % Complete job the task status changes to 'Not Started', and the % Complete goes from 100 to 0%.
The projects % Complete Calculation Method is set to 'Effort'.
With 'Effort' the 'Update % Complete' job is designed to calculate the task % complete and change the status based on it. If a task has an assignment with no Actuals or ETC (Effort) , the status will be 'Not Started' and 0% complete. This is working as designed.
The fact that allows you to temporarily mark the status of a task to completed by marking an assignment complete in Organizer -> Tasks is misleading to users since the status is later changed by the job. We are resolving this as CLRT-74872.