New Twiddle

controllers.application.js

export default Ember.Controller.extend({
  
  lat: 33.96216,
  lng: -118.31994,
  zoom: 9,
  
  currentJSON: JSON.parse('{"type":"FeatureCollection","features":[{"type":"LineString","coordinates":[[-118.31688,34.16942],[-118.30261,34.16875],[-118.28137,34.15103],[-118.26762,34.1137],[-118.22011,34.07866],[-118.21414,34.0516],[-118.22143,34.03424],[-118.21818,34.0296],[-118.1611,34.01114],[-118.09906,33.94473],[-118.10456,33.9223],[-118.10417,33.88213],[-118.08153,33.82105],[-118.08181,33.80344],[-118.09189,33.78329],[-118.089,33.77657],[-118.04017,33.77365],[-117.94881,33.70121],[-117.91615,33.68811],[-117.86672,33.68662],[-117.9159,33.68831],[-117.94878,33.70149],[-118.04055,33.77411],[-118.0886,33.77662],[-118.08139,33.82309],[-118.10327,33.87911],[-118.10516,33.90368],[-118.10364,33.92614],[-118.09553,33.94078],[-118.16049,34.01089],[-118.21912,34.03218],[-118.21389,34.05133],[-118.22019,34.07915],[-118.26708,34.11347],[-118.28215,34.15209],[-118.30274,34.15658],[-118.32612,34.15411],[-118.32953,34.16115],[-118.31688,34.16942]]}]}'),
  
  geoJSON1: JSON.parse('{"type":"FeatureCollection","features":[{"type":"LineString","coordinates":[[-118.31688,34.16942],[-118.30261,34.16875],[-118.28137,34.15103],[-118.26762,34.1137],[-118.08153,33.82105],[-118.08181,33.80344],[-118.09189,33.78329],[-118.089,33.77657],[-118.04017,33.77365],[-117.94881,33.70121],[-117.91615,33.68811],[-117.86672,33.68662],[-117.84639,33.67752],[-117.84603,33.6723],[-117.8421,33.67736],[-117.86597,33.68675],[-117.9159,33.68831],[-117.94878,33.70149],[-118.04055,33.77411],[-118.0886,33.77662],[-118.08139,33.82309],[-118.10327,33.87911],[-118.10516,33.90368],[-118.10364,33.92614],[-118.09553,33.94078],[-118.16049,34.01089],[-118.21912,34.03218],[-118.21389,34.05133],[-118.22019,34.07915],[-118.26708,34.11347],[-118.28215,34.15209],[-118.30274,34.15658],[-118.32612,34.15411],[-118.32953,34.16115],[-118.31688,34.16942]]}]}'),
  
  //This is identical to the previous json
  geoJSON2: JSON.parse('{"type":"FeatureCollection","features":[{"type":"LineString","coordinates":[[-118.31686,34.16942],[-118.30261,34.16875],[-118.28137,34.15103],[-118.26762,34.1137],[-118.22011,34.07866],[-118.21414,34.0516],[-118.22143,34.03424],[-118.21818,34.0296],[-118.1611,34.01114],[-118.09906,33.94473],[-118.10456,33.9223],[-118.10417,33.88213],[-118.08153,33.82105],[-118.08181,33.80344],[-118.09189,33.78329],[-118.089,33.77657],[-118.04017,33.77365],[-117.94881,33.70121],[-117.91615,33.68811],[-117.86672,33.68662],[-117.84639,33.67752],[-117.84603,33.6723],[-117.8421,33.67736],[-117.86597,33.68675],[-117.9159,33.68831],[-117.94878,33.70149],[-118.04055,33.77411],[-118.0886,33.77662],[-118.32612,34.15411],[-118.32953,34.16115],[-118.31688,34.16942]]}]}'),
  
  actions: {
    updateJsonTo1() {
      this.set("currentJSON", this.get("geoJSON1"));
    },
    updateJsonTo2() {
      this.set("currentJSON", this.get("geoJSON2"));
    }
  }
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

.leaflet-container {
    width: 100%;
    height: 300px;
    font-family: inherit;
}

templates.application.hbs

<h2>Click the button below to trigger the GeoJson prop to get updated</h2>

<p>Notice that even though it is the same valid GeoJSON, it doesn't display</p>

{{#leaflet-map lat=lat lng=lng zoom=zoom}}
    {{tile-layer url="http://{s}.basemaps.cartocdn.com/light_all/{z}/{x}/{y}.png"}}
  {{geojson-layer geoJSON=currentJSON}}
{{/leaflet-map}}

<button {{action 'updateJsonTo1'}}>Click To Update 1</button>
<button {{action 'updateJsonTo2'}}>Click To Update 2</button>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1",
    "ember-leaflet": "3.0.10"
  }
}