Fixed: when moving an element from a Reorderable List to another one that's empty, the element size was being reset to the default 100,100. This also happened is moving any element to the start of a it current list.

Scripts/Controls/ReorderableList/ReorderableListElement.cs

@@ -88,6 +88,10 @@ namespace UnityEngine.UI.Extensions
             _fakeElement = new GameObject("Fake").AddComponent<RectTransform>();
             _fakeElementLE = _fakeElement.gameObject.AddComponent<LayoutElement>();
 
+            //Set fake element initial size
+            _fakeElement.GetComponent<RectTransform>().sizeDelta = _draggingObjectOriginalSize;
+            _fakeElementLE.preferredHeight = _draggingObjectLE.preferredHeight;
+            _fakeElementLE.preferredWidth = _draggingObjectLE.preferredWidth;
 
             RefreshSizes();
 
@@ -327,4 +331,4 @@ namespace UnityEngine.UI.Extensions
             _rect = GetComponent<RectTransform>();
         }
     }
-}
+}