We have a course set up via the CoursePress Plugin, which has about 75 students. Our teachers have found that in the last few weeks, their feedback and the students grades have disappeared. However, the work that the students have submitted, has been retained. I.e. inward coming data has been retained, but 'outward' going data has disappeared.
For example: Have a look at the Assessments section. For an example of what has happened, you could look at Debra Wray's work. I can tell you that feedback was given to Debra Wray on 14th or 15th August. Her second task (Module 1) happened on 15th. On 17th August when I checked, her percentage had jumped to 0% and her feedback had disappeared.