growsumo.js

<script type='text/javascript'>(function(){var gs=document.createElement('script');gs.src='https://snippet.growsumo.com/growsumo.min.js';gs.type='text/javascript';gs.async ='true';gs.onload=gs.onreadystatechange=function(){var rs=this.readyState;if(rs&&rs!='complete'&&rs!='loaded')return;try{growsumo._initialize('pk_d9FOdhhfrKGLy9YCGYIVQJVqv6PdNIxf');}catch(e){}};var s=document.getElementsByTagName('script')[0];s.parentNode.insertBefore(gs,s);})();</script>
<script>

  jQuery(document).ready(function($) {
  
    // send signup to growsumo
    if (typeof growsumo != 'undefined') {
      growsumo.data.email = 'test@test.com';
      growsumo.data.customer_key = 123;
      console.log(growsumo);
      growsumo.createSignup();
    }
    
  });
</script>

The way that the tracking works is, it sets the partner key on a cookie on the grsm.io domain so even if your redirect isnt going to that spot the tracking will still work

I will give it a shot on my end as well and let you know if I find anything funky