The described is the default behavior of the Scheduler. By design the Scheduler renders the all day events or the events longer than 24 hours in the "All day" slot. If you need to display such events without the "All day" slot, you could use a Timeline view. On the linked demo
you can find examples of different Timeline views.
Another possibility is to create a custom view which matches the requirements of the project. Below you can find links with more information regarding creating custom views:
In case you need assistance in implementing Custom Scheduler view, I would recommend you our Professional services
. That team is focused on providing implementations, based on specific use case scenarios. Let us know if you are interested in cooperating with that team and we will put you into contact with them.