This issue has been resolved in recent Moodle upgrade.
We were made aware of a Turnitin bug that could allow students to access their mark in the Moodle Grades before the post date has passed.
The bug occured when a Turnitin assignment was hidden and then subsequently shown to students, which then breaks the connection between the Turnitin post date and the Moodle Grades ‘hidden until’ setting.
If you have previously hidden your Turnitin assignment and it is now shown to students, then editing the post date would synchronise with the Moodle Grades ‘hidden until’ setting.
Please note that students cannot view their feedback before the post date since this information is only held within the Turnitin Feedback Studio and not passed to Moodle. Feedback will only be revealed once the Turnitin post date has passed.
Turnitin resolve this bug in their latest Moodle plugin which we have installed.
For any help with get in touch the Learning Technology Support team.