I also had some troubles with the tree node, one of them is the issue that you are describing.
To solve it I added a container inside the tree node like this:
As you can see in the image, you can nest unlimited amount of tree nodes.
One issue that I didn’t found a solution yet is related with the update of the objects inside the tree node. While updating the objects, the tree node collapse without any warning. So if you are working with multiple tree nodes it can turn a mess very quickly.
I hope it helps! Best Regards,