There is currently an ongoing issue with accessing Turnitin related content directly from Blackboard Grade Centre links, this will show a 502 error page.
Staff workaround
Please go to your course and then look towards the bottom left menu and select ‘Turnitin Assignments’. Once this loads you will then be access all of the Turnitin content such as the similarity reports.
Student workaround
Please go onto your Blackboard course and go to the area that you originally submitted your Turnitin work to. This may be under a menu such as ‘Assessments’. Once there please select the ‘View/Complete’ option, from here it will give you access to your report.