LTI Advantage: 0 points score are recorded as empty score

For the tests below, a test tool named ZTest will be used. The tool is available at https://ztest.cengage.info/ztest/ Prerequisites: Add test tool Site is configured with at least one course Assign a user (instructor) to the manager role site-wide Configure a site tool with access to AGS Log in as an administrator Navigate to Site Administration > Plugins > Manage tools Click on configure a tool manually Fill the form as follow: Tool name: ZTest Tool url: https://ztest.cengage.info/ztest/lti11 Consumer key: moodle-testing Shared secret: ztest-secret In the Services section, set the Assignment and Grades service to: ‘use this service for grade sync and column management’ Confirm tool is saved successfully Add a ZTest link to the course Log in as instructor Navigate to course Turn editing ON Click Add an activity or resource and select external tool On the Add external tool page, select ZTest for preconfigured tool Activity Name: ZTest Assignment Privacy: check accept grades from the tool Grade: maximum points: 50 Save and verify the course is successfully added to the course Reproducing the issue: We'll verify that a 0 score is recorded as 0 not as an empty score. Login as Student in the Course Launch ZTest Assignment Locate custom_lineitem_url , and copy its value (something like {{{moodle}/mod/lti/services.php/{courseid}/lineitems/{gradeitemid}/lineitem?type_id={tooltypeid}|| Select the AnyCall tab (make sure your browser window is large enough the tabs appear). It lets you send arbitrary calls back to the tool consumer properly signed URL: paste the custom_lineitem_url value Modify the url by adding /scores at the end of the path, preserve the custom parameters. The url must end by /lineitem/scores?type_id={tooltypeid} Method: POST Content-Type: application/vnd.ims.lis.v1.score+json Payload should pre-fill with a JSON payload, verify it contains Userid should be the current student user id. scoreGiven: 0 scoreMaximum: 16 comment: commented Timestamp in ISO 8601 activityProgress: Completed gradingProgress: FullyGraded Press send Verify ZTest indicates the operation is successful (200) Navigate to Grades Verify the grade for ZTest Assignment is not a - but 0