Zephyr Scale REST API /rest/atm/1.0/testcase throws 500

I'm trying to create a test case for few projects, the create test case API works for other projects but throws 500 Internal Server Error without error message

POST /rest/atm/1.0/testcase HTTP/1.1
Content-Type: application/json

{
"projectKey": "FWEW",
"folder": "/Subject/Test",
"name": "Test",
"labels": [
"MANUAL"
],
"objective": "Test objective"
}