Over the past 10 days, some users have reported losing their list of calendar subscriptions in sogo (it appears in the left-hand pane of the sogo window, under the month calendar). It is not known how many people were affected. It is known that many/most people were not.
CTS staff are looking into restoration of calendar subscription lists from database backups, but this will take at least several additional days. Manually re-subscribing to calendars works and at present is the recommended way to reconstruct calendar subscriptions. Doing this is straightforward. Instructions can be found in Section V (page 22) of the user guide found at http://www2.potsdam.edu/cts/pdf/SOGoCalendar.pdf.