Reduced Test Case

I tried to create a very simple codePen : https://codepen.io/crevecoeur/pen/RwZzRKm

Bug Description

Describe how to recreate the bug. I create some events and a simple fullcalendar : eventOverlap: (stillEvent, movingEvent) => { stillEvent.setAllDay(false) movingEvent?.setAllDay(false) return true }

What do you expect to happen? I want the to change the moving event and the still event

What happens instead? The still event change but not the moving event

ScreenShot

All Day Event : movingEvent Long Event : stillEvent After i drag the event from Mon 01 to Mon 08

All Day Event : not changed

Long Event : changed