I found that 'my courses' is not working as expected. When non-member click the menu 'my courses', 'my courses' shows all courses which this member does not belong to.
Investigating this bug, I found that the view for my courses should be corrected as following.
In filter criteria in the view of my courses, following should be added: OG membership: Entity_type (= user)
Thanks for this great LMS module.