On May 11, 2014 (which was Mother's Day) my Lock Screen was saying that "tomorrow" would be Mother's Day. Then, on May 12 it said "today" was Mother's Day. However, when I checked my Calendar, I could clearly see that Mother's Day was May 11.
What's going on here? How do I fix it, and prevent it from affecting other calendar events?
Some notes about the phone and its configuration:
Make/Model: Nokia Lumia 920
OS Version: 8.10.12359.845
Date+Time Setting: 24-hour clock, set automatically, (UTC-05:00) Eastern Time (US & Canada)
Lock Screen "Choose an app to show detailed status": Calendar
Region: United States, English (United States)
Calendar is allowed to run in the background, but not when Battery Saver is on.
I tried [RIPS10's suggestion]. The reboot didn't help, but resetting the detailed item on the lock screen worked for Mother's Day. However, the problem has resurfaced today.
This doesn't just affect holidays - it appears to (at least) affect any all-day activity. I have a recurring Calendar item I set up myself for Patch Tuesdays, and on May 13 it's telling me that Patch Tuesday is "tomorrow".