Hey Christian,
Thanks for reaching out to us!
When creating an event that ends at midnight, you’ll need to actually set the end date to the following day at 12:00 am. If not, the system will assume that you selected an end time that was before the start time of the event and just save it to be the same as the start time.
But when creating the event to end the next day you probably don’t want that event to show up for both days on your calendar. If not, we do have a setting available in the Events > Settings > General tab called the “End of Day Cutoff” that will allow you to select times past midnight for the end of day so those night events don’t show on both days.
Let me know if this helps.
Thanks!