I'm getting this error on the last line

{
  "type": "error.SuiteScriptError",
  "name": "SSS_MISSING_REQD_ARGUMENT",
  "message": "DynamicRecord.commitLine: Missing a required argument: sublistId",
  "stack": [
    "<anonymous>(N/record/recordService.js)",
    "createItem(/SuiteScripts/New Stock Wizard/mos_newstockwizard_sl.js:182)",
    "onRequest(/SuiteScripts/New Stock Wizard/mos_newstockwizard_sl.js:252)"
  ],
  "cause": {
    "type": "internal error",
    "code": "SSS_MISSING_REQD_ARGUMENT",
    "details": "DynamicRecord.commitLine: Missing a required argument: sublistId",
    "userEvent": null,
    "stackTrace": [
      "<anonymous>(N/record/recordService.js)",
      "createItem(/SuiteScripts/New Stock Wizard/mos_newstockwizard_sl.js:182)",
      "onRequest(/SuiteScripts/New Stock Wizard/mos_newstockwizard_sl.js:252)"
    ],
    "notifyOff": false
  },
  "id": "",
  "notifyOff": false
}

but

sublistId

is definitely set (verified in the debugger as well)!?