Activity Code Values Disappeared

I opened the latest update of a Project in 8.2 EPPM, and the individual activity code values were gone. They are also gone in all of the other updates as well as the original Baseline schedule. Another user opened a schedule that he maintains, and the codes were gone there as well. I checked some other Projects and the codes values are gone in some of them as well. This is not happening in all of the projects on the EPPM database. After opening and closing P6 a few times, the codes came back. Any help explaining what is causing