The tree is not displayed when fetching data from API about vue.d3.tree HOT 3 OPEN

{
	"id": 0,
	"title": "Products",
	"children": [{
		"id": 1,
		"title": "Motivate up to down communication",
		"children": [{
			"id": 7,
			"title": "Ensure 100% of team members receive feedbacks quarterly"
		}, {
			"id": 8,
			"title": "Roll out anonymous feedback surveys from bottom to up quarterly"
		}]
	}, {
		"id": 2,
		"title": "Empower colleagues and thus improve products",
		"children": [{
			"id": 9,
			"title": "Track feedback from new sign-ups"
		}, {
			"id": 10,
			"title": "Schedule meetings of all department members every two weeks"
		}] 
	}]
}