At the moment, turning Global Targeting on restricts course visibility: only users that are marked as Course Catalog visitors can see the Courses even if the Targeting is off on the Course level.
User becomes a Course Catalog Visitor when they are added to the Learner List. If they are added to the Course Catalog by Course Enrollment, that does not make them Visitors, so these users will see only the Courses they are enrolled in.
In order to resolve this issue for every user, you should add them to the learner list. Currently, the workaround here would be either to manually add users one by one or to create an AD group with all the users in it and add it to the learner list.