This issue has been verified in Moodle 1.9 build 20080813. To reproduce the issue, it is needed a SCORM object set up to send Moodle a "completed/incomplete" status. Then setup the Moodle SCORM activity as follows:
Grading method: Learning objects
Number of attempts: unlimited attempts
Attempts grading: Highest attempt
Stage size: 1024x768, new Window, allow resize, allow scroll
Student skip content structure page: Always
Disable preview mode: Yes
Course structire display (TOC): Hidden
Hide navigation buttons: No
Auto Continue: No
Auto Update: Never
Now, attempt the SCORM activity as student "XY" without completing it. Return teacher and make sure the SCORM reports the status "incomplete" and the score is "0" in the SCORM activity report.
Once verified as above, access the Grader report: for the student "XY" no grade is showed. (i.e "-").
Login as student "XY" again and complete the SCORM module. Return teacher and make sure the SCORM now reports "completed" and the score is "1" in the SCORM activity report.
Once verified as above, access the Grader report: for the student "XY" still no grade is showed. (i.e "-").
in Grader report, Turn editing on. Click on the "edit" icon on the missing grade. In the Edit grade screen just press "Save changes" without any modifications.