We're using Sitefinity 6.3. The standard Events module has exhibited very odd behavior - we have made no modifications I'm aware of.
First of all, the time for the event changes constantly. (It may be timezone related, but it shouldn't be happening anyhow.) In the Events page list in the backend, I see an event for 20 Jun 1:00 PM - 5:00 PM. I click into it, and it shows the event as starting at 17:00 (5:00 PM). If I save it without changing anything, the Events page lists it as starting at 5:00 PM; I click into it, and it says the event starts and ends at 21:00 (9:00 PM). I change it to 1:00 - 5:00, and the Events page list says it's from 1:00 to 6:00 now.
All-day events also have issues saving correctly, with similar hour-shifting issues showing them as starting and ending on different days.
This culminates in issues displaying the dates to the end user, as well, especially for all-day events.
Is there a way this can either be fixed, or that we can overwrite?