I've created a Shared Calender and shared it with a friend.
Working fine until recently (I suspect an update from Windows Phone 8.1 to 10).
Now when I check my calendar online (owa, so not in any client) all appointments are fine. The "all day" events show up as one day. As expected.
However, when my friend opens the same calendar (also online, owa). The "all day" events show up as two day events?????? We are in the same timezone and we checked the calendar settings online (owa). The seem to be te same.