Google Maps for ExpressionEngine Multiple Markers - incorrect display

Question

ExpressionEngine 2.9.2 Google Maps for ExpressionEngine 3.3.8 Geocoder 1.2.0

I have a channel for branches and on the single entry page the map correctly displays the branches location using this code.

<div class="embed-container">
{exp:gmap:init id="map" scrollwheel="false"  style="width:1200px;height:460px"}

{exp:gmap:center id="map" address="{branch_address} {branch_city}"}
</div>

{exp:gmap:marker id="map" latitude="{branch_latitude}" longitude="{branch_longitude}" zoom="13"}

However on the landing page where I need to have a map showing all branches across Canada it is not working correctly. There are currently 27 branches but on the google map only 4 are displaying and they are not in the correct location. Furthermore the infobox for all pins contains exactly the same data rather than the data for that pins location.

Template code:

{exp:channel:entries channel="branches" disable="member_data|pagination|categories|category_fields" limit="300"}

 {exp:gmap:marker 
  id="map" 
  latitude="{branch_latitude}" 
  longitude="{branch_longitude}"
  duplicate_markers="false"
  icon="/images/map-pin.png"
  geocode="true" 
  clustering="false"
  latitude="48" 
  longitude="-83"
  limit="100"

  infobox="true"
  offsetY="-40"
  offsetX="0"
  class="entry-{entry_id} ui-infobox-dark"
  closeBoxMargin="5px"
}
  <div class="ui-infobox-content">
    <h4>{title}</h4>
    {branch_address} <br>
    {branch_city} {branch_province} <br>
    {branch_postcode} <br>
    Work Phone: {branch_phone} <br>
    Toll Free: {branch_toll_free} <br>
    Fax Number: {branch_fax}
  </div>
{/exp:gmap:marker}

{!--
// add active class to branch card to highlight it.
--}
{exp:gmap:event id="map"}
  $('.block article.entry{entry_id}').addClass('active');

  $( ".ui-infobox-dark  img" ).click(function() {
    $('.block article').removeClass('active');
  });

{/exp:gmap:event}

{/exp:channel:entries}

I've tried a number of different approaches and scoured the documentation but cannot seem to figure out what I'm doing wrong. Please advise.