Emma, we face this same issue in Moodle 2.5.5+. Issue exists with both SCORM packages and Lesson activities. I hope someone else has more information to share.
Courses and course formats
The problem of Display of Course Completion
دا بحث کولپ شوی دی نو تاسو نشئ کولی دې ته نور ځواب ورکړئ.