The error message oauth_consumer_key value is missing or not valid may indicate that the Consumer Key (account ID) entered on your Learning Management System's (LMS) configuration page may be incorrect.
Please make sure that the Consumer Key is set to the correct Turnitin account ID for your institution. We also recommend re-entering the account ID to remove any whitespace that may be present.
More information on how to configure your LTI 1.1 integration can be found in our Help Guides: Configuring Feedback Studio in LTI 1.1 .