There must be something I am missing 
//Get issue "TNP-11"
var tnp11 = await _jira.Issues.GetIssueAsync("TNP-11");
var customFields = tnp11.CustomFields;
var a = customFields["Rank"]; //this works fine, I get the right object in a
var b = custFields["IssueLinkId"]; //this DOES NOT work, variable b will be null
var c = tnp11.CustomFields.FirstOrDefault(f => f.Name == "IssueLinkId"); //this works again
Why is 'b' null while 'c' is not?
Seemingly the [] operator has an issue with my custom field name "IssueLinkId".
thanks for your help
