On behalf of Turnitin I'm pleased to announce that Blackboard LTI customers who are using Blackboard version 3700.9.0 and above are now able to use LTI 1.3 for Turnitin integrations. This version addresses many of the known issues that were raised with the Blackboard LTI 1.1 integration. Adding support for LTI Advantage will improve usability of the Blackboard LTI integration while also enabling a more secure transfer of student data between Blackboard and Turnitin.
Blackboard customers using Turnitin will not will not be forced to migrate to LTI 1.3 anytime soon, with the caveat that LTI 1.3 with Advantage is the only integration that supports the new Ultra experience and Ultra Course view. Check out the administrator guidance to see what's new as well as the list of resolved issues:
Release notes can be found here: https://help.turnitin.com/release-notes/lti-release-notes.htm#2019-October-2nd and additional questions can be asked in the comments or on the Turnitin Educator Network.