SCORM 2004 - cmi.completion_status = completed disables lms scorm communication

i use the moodle-latest, as usual.

basic steps to recreating the problem:
1 create a scorm 2004 course, add a scorm and set cmi.completion_status to completed
2 re-enter the lesson by clicking the "ENTER COURSE" button, but without checking the start new attempt. the lms should not be available to the content. strange thing is, there are no javascript errors whatsoever. if you enter the course by clicking on the link (the organization's name), the lms is initialized fine, and everything works.

any help?