We have had several professors at our institution suddenly have their grades disappear. All the rows and columns are there but the data is empty. If you click into a cell it still doesn't show a score value. The data is still there because an export of the grade book shows everything. We resolved the issue by changing the date the term ends to the next day. Has anyone else seen this happen? Why is changing the end of the term the fix? Why would grades vanish before the conclusion of the term?