Cannot drag and drop scene objects into Custom Inspector GUI

[vickyyy0221]

Hi, I am editing a Dialogue Editor for my case. I added an end trigger object as “trigger next button” for each dialogue item. When I tried to drag object from scene to Inspector, it won’t let me drag it in, but it works if I drag the same type of object already save in folder.
Dragging scene object to “End Trigger” field:

Dragging same saved prefab from folder:

Can anyone explain why and how to fix it?

using UnityEngine;

[System.Serializable] //needed to make ScriptableObject out of this class
public class DialogueElement
{
    // CharacterID is an index to the according character
    public int CharacterID;

    //public enum Characters { CharacterA, CharacterB}; //no longer needed
    public enum AvatarPos { left, right };

    [Header("CHARACTER")]
    //public Characters Character;
    public AvatarPos CharacterPosition;
    public Sprite CharacterPic;
    public GameObject EndTrigger;

    [Header("DIALOGUE")]
    [Tooltip("What the character is saying")]
    [TextArea]
    public string DialogueText;
    public GUIStyle DialogueTextStyle;
    [Tooltip("How many letters per second")]
    public float TextPlayBackSpeed;

    public AudioClip PlayBackSoundFile;
}

[spiney199]

Long story short is assets cannot reference scene objects. It’s an inherent Unity limitation due to a number of reasons.

You generally need to devise some kind of ID registration system to cross this bridge from assets to scenes.