I have been having a similar problem. I wrote to Andreas Grabs, developer of the module and explained my predicament. He pointed out that it was a roles permission problem.
The lecturers, though, students in the course with the feedback module, were course creators at the system level, hence they would be course creators in every child course - meaning course on the system.
I would therefore advise you to check whether or not the teachers are course creators/teachers in a context that would include the immediate context of your course with the feedback module, for eg. are the teachers course creators at the level of the course category or at the system level?
If they must be course creators at the level of the course category you may need to move the course with the feedback module to another course category.
If the teachers are course creators at the system level you should reconsider the wisdom of this as it gives them course creator access to every course on the moodle system.
The roles paradigm though exciting in the possibilities does take time to work through.