We're using LTI assessments with a Turnitin anti-plagiarism check integration, however this means that rubrics is not an option in the assessment settings.

Without rubrics we cannot use this integration. Please allow the option to include rubrics as per a normal assessment.

(Note that this is not with the inbuilt Turnitin integration which only supports one account type, so I imagine this missing rubrics problem is true of any LTI assessment).