Summary:
User has entered time against a specific project. None of the reports returns the time entered by the user against the Project.

Cause:
This is most likely the user would have entered time against the project which is ‘Multiple clients for project cost allocation’ where the allocation percentage associated with all the clients in that project is zero.
 
Solution:
If it is cost allocation project then the allocation percentage associated with the clients should be greater than zero in order to show the time entered by the user against that project in the report as the cost is shared among the clients in cost allocation method.