Project 2013 – Work hours showing as 0 in resource usage view for assigned resources!!

There are instances when we see that even though resources are assigned on the tasks, yet in Resource Usage or Task Usage Views you see 0 hrs. assigned to those resource. Refer to the snapshot below, even though resources are assigned yet in Resource Usage their Work Hours is shown as 0.

Workaround : Turn on the Calculation Mode after each edits by -> File -> Options -> Schedule -> Calculate Project after each edit – turn it ON. This will fix the above problem.