Exported Excel file does not retain custom date format (MM-dd-yyyy)

###### This is my code

const paymentDetails = async (req, res) => {
  try {
    const {
      from_date = null,
      to_date = null,
      location = "",
      provider = "",
      date_option = null,
      practice = "",
      payerType = null,
      dates = null,
      showBal = null,
      paymentMethod = null,
      batch = null,
      selectedType,
      groupBy,
      check_flag
    } = req.query || {};

    let payment_Method_Filter = paymentMethod?.value || null;

    if (location?.id) {
      // conditions.push(APSC.hospital_id = ${location?.id});
      // Location_filter = location?.id;
    }

    if (provider) {
      // conditions.push(APSC.provider_id = ${provider?.id}
);
      // Provider_filter = provider?.id;
    }

    let clickedField = null;
    let groupPayerType = null;
    if (groupBy == "Payment Method") {
      clickedField = selectedType;
    } else if (groupBy == "Payer Type") {
      groupPayerType = selectedType;
    }

    // const results = await sequelize.query(
    //   SELECT * FROM generate_payment_detail_report(
    //   :date_option::TEXT,
    //   :from_date::DATE,
    //   :to_date::DATE,
    //   :payment_method_option::TEXT,
    //   :payer_type_option::TEXT,
    //   :practice_id_option ::NUMERIC,
    //   :show_balance::TEXT,
    //   :param_batch_id::TEXT),
    //   {
    //     replacements: {
    //       date_option: dates || null,
    //       from_date: from_date || null,
    //       to_date: to_date || null,
    //       // practice_id: practice_id || null,
    //       param_batch_id: batch || null,
    //       payment_method_option:
    //         paymentMethod === "Other" || paymentMethod === "Unknown"
    //           ? paymentMethod
    //           : paymentMethod
    //           ? paymentMethod.toLowerCase()
    //           : "All",
    //       payer_type_option:
    //         payerType === "All"
    //           ? payerType
    //           : payerType
    //           ? payerType.toLowerCase()
    //           : null,
    //       show_balance: showBal || "All",
    //       practice_id_option: practice?.id || null,
    //     },
    //     type: sequelize.QueryTypes.SELECT,
    //   }
    // );

    const results = await sequelize.query(
      `SELECT * FROM payment_detail_from_summary_with_flag(
      :date_option::TEXT,      
      :from_date::DATE,        
      :to_date::DATE,
      :payment_method_option::TEXT,
      :payer_type_option::TEXT,  
      :practice_id_option ::NUMERIC,
      :show_balance::TEXT,
      :batch_option::TEXT,
      :check_flag::BOOLEAN)`,
      {
        replacements: {
          date_option: dates ? "Custom" : null,
          from_date: from_date || null,
          to_date: to_date || null,
          // practice_id: practice_id || null,
          batch_option: batch || null,
          payment_method_option: clickedField
            ? clickedField
            : paymentMethod
              ? payment_Method_Filter.toLowerCase()
              : null,
          payer_type_option: groupPayerType
            ? groupPayerType
            : payerType === "All"
              ? payerType
              : payerType
                ? payerType.toLowerCase()
                : null,
          show_balance: showBal || null,
          practice_id_option: practice?.id || null,
          check_flag: check_flag
        },
        type: sequelize.QueryTypes.SELECT,
      }
    );

    const flexMonsterData = {
      mapping: {
        payment_type: {
          type: "string",
          caption: "Payment Type",
        },
        payment_id: { type: "string", caption: "Payment ID" },
        post_date: {
          type: "date string",
          format: "MM-dd-yyyy",
          caption: "Post Date",
        },
        payer_name: {
          type: "string",
          caption: "Payer Name",
        },
        ref_number: {
          type: "string",
          caption: "Ref No.",
        },
        notes: {
          type: "string",
          caption: "Notes",
        },

        amount: {
          type: "number",
          caption: "Applied Amount",
        },
        unapplied: { type: "number", label: "Unapplied" },
        total_amount: { type: "number", label: "Total Amount" },
      },
      slice: {
        rows: [
          { uniqueName: "payer_type", caption: "Payer Type" },
          { uniqueName: "payment_method", caption: "Payment Method" },
        ],
        columns: [{ uniqueName: "[Measures]" }],
        measures: [
          {
            uniqueName: "amount",
            aggregation: "sum",
            caption: "Applied Amount",
          },
          {
            uniqueName: "unapplied",
            aggregation: "sum",
            caption: "Unapplied Amount",
          },
          {
            uniqueName: "total_amount",
            aggregation: "sum",
            caption: "Total Amount",
          },
        ],
        drillThrough: [ // 👈 Predefined visible fields in drill-through
    "payer_name",
    "payment_type",
    "payment_id",
    "payer_type",
    "payment_method",
    "post_date",
    "ref_number",
    "total_amount",
    "amount",
    "unapplied"
  ],
      },

      options: {
        viewType: "grid",
        showAggregationLabels: false,
        grid: {
          type: "compact",
          showTotals: false,
        },
        datePattern: "MM-dd-yyyy",
        showFilter: false,
        showHeaders: true,
        configuratorButton: false,
        showGrandTotals: true, // Disable grand totals
        drillThrough: true,
        drillThroughMaxRows: 1000, // Increase if needed
        formats: [
          {
            name: "",
            thousandsSeparator: ",",
            decimalSeparator: ".",
            decimalPlaces: 2,
            nullValue: "-",
          },
          {
            name: "currency",
            currencySymbol: "$",
            currencySymbolAlign: "left",
            decimalPlaces: 2,
          },
          {
            name: "date string",
            format: "MM-dd-yyyy",
            nullValue: "-",
            applyTo: "post_date",
          },
        ],
      },
    };
    const data = map(results, (row) => ({
      ...row || {},
      post_date: moment(row.post_date).format("MM-DD-YYYY"),
      amount: formatNumber(row.amount),
      unapplied: formatNumber(row.unapplied),
      total_amount: formatNumber(row.total_amount)
    }))
    const HeaderData = {
      PracticeName : practice?.practice_name || '',
      fromDate : from_date || '',
      toDate : to_date || '',
      dateType : 'Posting Date',
    }
    return res.status(200).send({ data: data, flexMonsterData ,HeaderData : HeaderData});
  } catch (error) {
    console.log(error);
    console.error("Error fetching report:", error.message);
    return res.status(500).send({ message: "Internal Server Error", Error: error.message });
  }
};

 
 
### Frontend Side

 
### Exported Excel

 
 

I’m encountering an issue with date formatting in exported Excel files using Flexmonster.

• On the backend, I'm sending date strings in the format: MM-dd-yyyy (e.g., 07-11-2025).

• On the Flexmonster grid (frontend), the dates are displayed correctly as MM-dd-yyyy.

• However, when I export the grid to Excel, the dates in the Excel file appear as dd-MM-yyyy or dd/MM/yyyy, depending on the system's locale or Excel settings.

This mismatch between displayed format and exported format is causing confusion for end users.

What I’ve tried:

• Explicitly setting the field type to "date string" in the mapping.

• Confirming the correct format in the grid.

• Using applyFormatting: false in the export config (no change to date format).

Expected behavior:

• The exported Excel file should preserve the MM-dd-yyyy format as displayed in the grid.

Please let me know:

• How can I enforce a consistent MM-dd-yyyy format in the exported Excel file?

• Is there a setting or workaround to ensure exported date formats match the frontend view?