Analytics Bulk API - Export Data (Asynchronous) JSON_PARSE_ERROR only on first try

Analytics Bulk API - Export Data (Asynchronous) JSON_PARSE_ERROR only on first try

Hello,

inside a custom function in Zoho Flow I want to create an export job, but I get an error when I send the request.
However, this error only occurs the first time, if I call the same custom function again in the flow I don't get an error message anymore.

I use this API endpoint:
GET https://<ZohoAnalytics_Server_URI>/restapi/v2/bulk/workspaces/<workspace-id>/views/<view-id>/data

I get this response:

{"status":"failure","summary":"JSON_PARSE_ERROR","data":{"errorCode":8534,"errorMessage":"Invalid JSON Format."}

Code of the custom function:

map createAnalyticsExportJob(int workspaceId, int viewId)
{
returnValue = Map();
header = Map();
header.put("ZANALYTICS-ORGID",XXXXXXXX);
config = "%7B%22responseFormat%22%3A%20%22json%22%2C%22callbackUrl%22%3A%20%22https%3A%2F%2Fflow.zoho.eu%2F20082214652%2Fflow%2Fwebhook%2Fincoming%3Fzapikey%3D1001.7dfasdadadadadsasdasdadadadadasdadasdadsadasdasdadsasdasdasdadscc1bfe5d5d8de9a0e4d9e5968451b.ed07b67c38b360b1820707b450174492%26isdebug%3Dfalse%22%7D";
createJobResponse = invokeurl
[
    url :"https://analyticsapi.zoho.eu/restapi/v2/bulk/workspaces/" + workspaceId + "/views/" + viewId + "/data?CONFIG=" + config
    type :GET
    headers:header
    connection:"analytics"
];
if(createJobResponse.get("status").equalsIgnoreCase("success"))
{
    returnValue.put("message","Line 35: Die Anfrage für eine Erstellung des Exports aus Analytics wurde erfolgreich gestellt! " + createJobResponse);
    returnValue.put("isError","false");
}
else
{
    returnValue.put("message","Line 40: Während der Anfrage für eine Erstellung des Exports aus Analytics ist ein Fehler aufgetreten! " + createJobResponse);
    returnValue.put("isError","true");
}
return returnValue;
}