Noticed that when we create an item in the Scheduler and check the All Day checkbox the resulting Recurrence Rule adds an extra day. This leads to an extra day showing up in the Scheduler interface. We don't set any specific timezone on the scheduler, we actually hide all the timezone options in the interface as it just confuses our users:
//hide the timezone selections
e.container.find("[data-role=timezoneeditor]").hide();
e.container.find("[data-role=timezoneeditor]").parent('div').hide();
$('label[for="StartTimezone"]').hide();
$('label[for="StartTimezone"]').parent('div').hide();
e.container.find("label[for='EndTimezone']").hide();
e.container.find("label[for='EndTimezone']").parent('div').hide();
For example I create an event that starts on March 28, 2019, repeats daily and ends on Mar 30 3019 and check "All Day" checkbox - the resulting recurrence rule is saved as FREQ=DAILY;UNTIL=20190331T025959Z. In the scheduler we see the event on the 31st of March.
I can send you the code we have for the CustomEditortemplate.cshtml. The clocks moved forward an hour this month (now Atlantic Daylight Time ADT) if that provides a clue, can't be assured if this was happening before the time change or not though...
Also start and end times are saved as 2019-03-28 00:00:00.000 - zeros for the time portion in our SQL Server - when I look at the models in EventSchedule_Create([DataSourceRequest] DataSourceRequest request, IEnumerable<EventScheduleViewModel> models) the start time and end time are 12:00:00 AM so this might be Entity Framework or SQL server ?