If a task has been completed, staff are unable to post time to that task.
This makes sense in theory, but does not work if staff are posting time entries late. If staff are catching up with time at the end of the day, the task will not be in the dropdown if it's been marked as complete. This is more apparent for senior staff & partners, who simply do not have the time to do an hour-by-hour timesheet.
I suggest that if a task was completed on 30th September, for example, staff should be able to post time to this task if completing their timesheet up to this date. For example, if the current date is 4th October and I'm posting a time entry for 28th September, that original task should show on my dropdown menu for the time posting, since it was not marked as completed at this date.