Posting a user to Jira Cloud failing intermittently

Posting a user in the Jira cloud Sandbox, gets failed few of the times. Like 5 out of 10 times.

Request json - >

  "emailAddress": "",
  "displayName": "SoapFirstName SResInstance",
  "name": ""

Response Code 400
Response body:

  "message": "Failed to create the object.",
  "providerMessage": "{errorMessages=[The request failed. We're not sure what went wrong. Try again and if the problem persists, contact Jira support.], errors={}}",
  "requestId": "5d022157e4b09916c19c1d87"

But the user is created in Jira. Pls advice why this is happening. When will this issue be resolved.