Coroutine for WWW call not resuming

Hi!

I want to make an API call using the WWW class. In order to do this I start a coroutine, but a lot of the times it isn't resumed, it works half of the time.

I start the coroutine like this:

 StartCoroutine(APIcalls.Instance.CreateMatch(serverName));

And the function the coroutine is calling looks like this:

     public IEnumerator CreateMatch(string serverName){
         Debug.Log ("Sending data to API...");
 
         WWWForm form = new WWWForm ();
         form.AddField("name",serverName);
         
         WWW postURL = new WWW(GameSettings.ApiURL+"/api/matches", form);
         yield return postURL;
 
         Debug.Log ("POST call complete?");
 
         if (!string.IsNullOrEmpty(postURL.text)) {
             var match = JSON.Parse (postURL.text);
             Debug.Log ("Created match with id: " + match ["match_id"]);
         }
         else {
             Debug.Log ("Error: "+postURL.error);
         }
     }

So half of the time I don't even get the log "POST call complete?", like the coroutine never resumes after the yield.

The call reaches the API route, I can see things happening in my api, but the coroutines is not resumed.

Can you see what might be causing this error?

Thanks for the help!