Creating Matrix Items

Hi,

I am having an issue creating matrix child items in suitescript 2 and was wondering if anybody has come across a solution (even in Suitescript 1).
The matrix parent is being created successfully.

The error I am getting is

"msg": {                  "type": "error.SuiteScriptError",                  "name": "UNEXPECTED_ERROR",                  "message": null,                  "stack": [                      "anonymous(N/serverRecordService)",                      "onRequest(/SuiteScripts/SuiteFunction/RPS/SF_create_item_option2.js:80)"                  ],                  "cause": {                      "type": "internal error",                      "code": "UNEXPECTED_ERROR",                      "details": null,                      "userEvent": null,                      "stackTrace": [                          "anonymous(N/serverRecordService)",                          "onRequest(/SuiteScripts/SuiteFunction/RPS/SF_create_item_option2.js:80)"                      ],                      "notifyOff": false                  },                  "id": "9498b166-eb08-44c4-ac1b-3c78c485ee33-2d323031392e30322e3139",                  "notifyOff": false,                  "userFacing": false              }