Power BI Rest API Crashing on ExportToFileInGroupAsync

Question

I'm attempting to use the microsoft power BI API to export a report a PDF file version. I'm able to successfully authenticate power BI with azure and can get a bearer token before making this call.

The ExportToFileInGroupAsync(reportId, groupId, exportRequest) is throwing an 'Object reference not set to an instance of an object error.' on the ExportToFileInGroupAsync line. I tried with ExportToFileAsync and the same thing is happening.

I've verified that the groupId and reportId are correct, if I missed that I would expect it to be a 404 error instead of simply crashing.

Has anyone encountered this before?

//get token - working and grabbing bearer
var tokenCredentials = new TokenCredentials(await GetToken(), "Bearer");

//initiate powerBI Client
client = new PowerBIClient(new Uri("https://api.powerbi.com/"), tokenCredentials);

try
{
    var exportRequest = new ExportReportRequest
    {
        Format = format
    };

    if(_currentAccessToken == null) 
        await Authenticate();
    // The 'Client' object is an instance of the Power BI .NET SDK
    var export = await client.Reports.ExportToFileInGroupAsync(reportId, groupId, exportRequest);

    // Save the export ID, you'll need it for polling and getting the exported file
     return export.Id;
}
catch
{
     throw;
}