Case: when tree is hidden (for example inside tab or modal), it is not rendered when it becomes visible.
Solution: after it becomes visible (preferably using setTimeout) - call
tree.sizeChanged(), which recalculates the rendered nodes according to the actual viewport size.
Maybe you are not supplying unique IDs to the nodes.
The tree maintains its state by using IDs, and if you don't supply ones the tree will generate random ones automatically. Which means that if you update the data - the state will be lost.
See Drag & Drop page, there's a section about mobile.
See scrollContainer option in Options for more information
Updated less than a minute ago