We were having a similar problem and found two different scenarios
occurring. 1 - The timesheet defaults to only showing 100 tasks but you
can have that changed to 250 by calling support. 2 - If a task remains
on timesheet for a certain period of time without any time being
recorded to it, that task will fall off the timesheet. I do not know
what that time period is. If you remove that person from the assignments
and then reassign it to them, the task will then show up on the
timesheet. I wish I...