We have identified a bug in Turnitin rubrics, in which using the sliding scale to update a score does not update the number correctly.
Therefore, we recommend that, if you use the rubric slider to apply a grade, you should click on the rubric slider scale circle (please see the screenshot below) once you have positioned it, in order to fix the number. This should allow you to apply the grade without issues.
Turnitin is planning to address the issue in a future update of the product.
If you have any questions or concerns, please email firstname.lastname@example.org.