Why is my Project Task not listed in the Deleted Records?

Sometimes mistakes happen and a Project Task (pm_project_task) is deleted on accident. Admins may check in the Deleted Records (System Definition > Deleted Records) to find nothing for the particular Project Task.

This is currently the expected behavior and could have happened two different ways:

1. If a Project Task is deleted through the Planning Console, there will be no Deleted Record created as it skips the Audit and Business Rules.
2. The Audit can also be skipped if the entire Project is deleted and the Project Tasks are cascade deleted.

This has been done due to performance reasons.
To fix the first scenario, you can enable a property to allow Business Rules to fire on the Planning Console. This will create Audit records.

You can change this in Project > Settings > Preferences - Project

Set this Preference to Yes:
'Enable firing of Business Rules on save from Planning Console. This property will be applicable only during insert and delete of tasks and relations.'

Currently, while this is the expected behavior, always adding deleted Project Tasks to the Deleted Records is being looked into as a Product Enhancement in PRB832946.