There is a bug in version 2.0.5
When you have time spent set to required when you submit a ticket as non-administrator/non-manager there is a js error that prevents you from submitting the form.
Basically it comes from this line in the newticket/form.php
if ($timespentMandatory) { ats_ticket_cansubmit = ($('#ats-timespent').val() > 0) }
The ats-stimespent is null and you can't do null.val() -> this triggers the error.
If you change it to:
if ($timespentMandatory) { ats_ticket_cansubmit = ($('#ats-timespent') && $('#ats-timespent').val() > 0) }
Then it should be fine.