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Drag & Drop fails with "n is undefined" error when using Lazy Loading on dynamically loaded nodes (Error on Le

1. Version: v31.2.12 (Assuming latest relevant version)


Environment: Vanilla JavaScript / Web Application


2. Description of the Issue

The Drag & Drop functionality (allowDragAndDrop: true) consistently fails with a JavaScript error when attempting to drag a node that was loaded dynamically via the Lazy Loading mechanism (loadOnDemand: true / data source mapping).


Error Manifestation: When dragging a node from a deeper level (typically Level 3 or higher) to any target, the application throws an error upon dropping the node.


Console Error: "Uncaught TypeError: Cannot read properties of undefined (reading 'length')" (The error points to n.length inside the minified ej2.min.js, likely within the internal data management/D&D logic).


3. Steps to Reproduce

Initialize the TreeView component with the fields mapping configured for Lazy Loading.


Expand a Level 1 node (e.g., UUID: 584b402c-...). This loads its Level 2 children.


Expand a Level 2 node (e.g., UUID: 645ce98c-...). This loads its Level 3 children.


Attempt to drag any node from Level 3 (e.g., 30873618-... or 6c357399-...) and drop it onto any target node (Level 1, Level 2, or another Level 3 node).


4. Workaround (Critical Proof)

The issue does not occur if the entire tree structure is loaded initially (Eager Loading), even for deep levels.


This strongly suggests an issue in the internal data synchronization or node reference resolution within the Syncfusion Data Manager when handling nodes loaded asynchronously via loadOnDemand.


More in attached document.