New Twiddle

controllers.application.js

export default Ember.Controller.extend({
  
  lat: -27.5555,
  lng: 152.94703,
  zoom: 7,
  
  test1:[-27.5555, 152.94703],
  test2:[-27.69149, 153.01561],
  test3:[-28.5, 153.01561],
  test4:[-28.5, 150.01561],
  
  defaultMarkerIcon: L.icon({
		iconUrl: 'http://img4.imagetitan.com/img4/small/16/16_marker-icon-orange(1).png',
		iconSize: [25, 41],
		iconAnchor: [12, 41],
		popupAnchor: [1, -34],
		tooltipAnchor: [16, -28]
	}),

});

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

{{#leaflet-map lat=lat lng=lng zoom=zoom}}
    {{tile-layer url="http://{s}.basemaps.cartocdn.com/light_all/{z}/{x}/{y}.png"}}
    
    {{#marker-layer location=test1 icon=defaultMarkerIcon}}
        {{#tooltip-layer permanent=true}}
            I seem to be incorrectly positioned<br>
            on first load. Zooming fixes this
        {{/tooltip-layer}}
    {{/marker-layer}}
	
    {{#marker-layer location=test2 icon=defaultMarkerIcon}}
        {{#tooltip-layer permanent=true}}
            I seem to be incorrectly positioned<br>
            on first load. Zooming fixes this
        {{/tooltip-layer}}
    {{/marker-layer}}
    
    {{#marker-layer location=test3 icon=defaultMarkerIcon}}
        {{#tooltip-layer permanent=true}}
            I seem to be incorrectly positioned<br>
            on first load. Zooming fixes this
        {{/tooltip-layer}}
    {{/marker-layer}}
    
    {{#marker-layer location=test4 icon=defaultMarkerIcon}}
        {{#tooltip-layer permanent=true}}
            I seem to be OK?
        {{/tooltip-layer}}
    {{/marker-layer}}
{{/leaflet-map}}

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": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "2.12.1",
    "ember-leaflet": "3.0.18"
  }
}