Unexpected error when using submitFields to edit transaction

Hello everyone!

I'm developing a Map/reduce script to set some custom values on Finance Charge Invoices, where I use Record.submitFields in the map() entry point to set those. It looks something like this:

const map = (context) => {
    try {
      const invoiceData = JSON.parse(context.value);
      const fields = getFields(invoiceData);

      record.submitFields({
        id: invoiceData.id,
        type: 'invoice',
        values: fields,
        options: {
          enableSourcing: true,
          ignoreMandatoryFields: true,
        },
      });


      context.write({
        key: invoiceData.id,
        value: JSON.stringify({ ...invoiceData, ...fields }),
      });
    } catch (e) {
      log.error('Map error', e);
    }
  };

When running said script, it logs an unexpected error on the submitFields line:

{
   type: "error.SuiteScriptError",
   name: "UNEXPECTED_ERROR",
   message: "An unexpected SuiteScript error has occurred",
   stack: [
      "Error\n    at suitescript/resources/javascript/record/recordImpl.js:156:24\n    at Object.submitFields (suitescript/resources/javascript/record/recordImpl.js:154:30)\n    at Object.map (/SuiteScripts/AdiScripts/AD - HN - Localization/AD - HN - Scripts/AD - HN - Process Finance Charges/ad_hn_process_finance_charges_mr.js:302:14)"
   ],
   cause: {
      type: "internal error",
      code: "UNEXPECTED_ERROR",
      details: "An unexpected SuiteScript error has occurred",
      userEvent: null,