Any time a user tries to click the "Add submission" button in any assignment, we're receiving the error "Invalid response value detected". Changing settings on assignment, course, and user does not seem to have any effect. Users are able to access quizzes and discussions without errors.
Note that we doe have the Poodll feedback plugin installed. We are receiving the error even when disabling that feedback method for a particular assignment.
Any thoughts on further testing we can do to get a more detailed response from the system?