I had the DST issue, which is no longer an issue on my NL 920, however another has cropped up.
Since DST started here (Germany), single, future calendar entries began disappearing from my phone. Currently all single, future, newly added calendar entries are disappearing. They will show up in my calendar temporarily after saving the appointment details, but will disappear within 1-7 days. Recurring events are unaffected, but every meeting, reminder, or other event that I have entered via the calendar in the past week have simply disappeared. I suspected previously that the issue only impacted those calendar events that contained special characters (my preferred phone language is English, but I often add German street addresses), however I've since lost two appointments for next week that contained no special characters.
Interestingly, appointments added prior to the past few weeks haven't been impacted. I have appointments coming up in May, June, and July that I added in January and they're all intact, however my phone claims I have only recurring appointments this week and next whereas the paper diary I've had to resort to keeping confirms otherwise.