Ionic List Group BY

Ionic Framework ionic-v3
1

I’m struggling with group by for a list. My JSON data is an array of objects, each object is an event with a title, description and start time. I want to group by start time. The JSON below should be displayed in a list, with 1 header showing 1 item, and another header showing 2 items. I’m willing to restructure the JSON if necessary.
The error I get is

TypeError: undefined is not an object (evaluating '_co.item.event_title')

The code:

<ion-list ng-repeat="(key, value) in items | groupBy: 'start_time'">
  <div class="item item-divider">
    <h1>{{key}}</h1>
  </div>
  <h3  ng-repeat="item in value">{{item.event_title}}</h3>
  	<div>
  		{{item.event_description}}
  	</div>
</ion-list>

JSON DATA (I’m not having any problem with the provider, I have plenty of lists working

[
	{
		"event_id": 1,
		"event_title": "Test",
		"event_description": "This is a test",
		"event_date": "2018-03-14",
		"start_time": "13:00:00",
		"end_time": "14:30:00"
	},
	{
		"event_id": 2,
		"event_title": "Test2",
		"event_description": "This is a test 2",
		"event_date": "2018-03-14",
		"start_time": "15:30:00",
		"end_time": "17:00:00"
	},
	{
		"event_id": 2,
		"event_title": "Test 3",
		"event_description": "This is a test 3",
		"event_date": "2018-03-14",
		"start_time": "15:30:00",
		"end_time": "17:00:00"
	}
]
3

I’ve managed to make a group by, following this tutorial: https://robferguson.org/blog/2018/09/28/ionic-3-filtering-sorting-and-pipes/