The issue appears to be how the datatables library handles rendering. It applies the styles after rendering the data, which appears to be causing it to skip the first column.

You can try applying the formatting during the drawCallback.

$(myTable).DataTable({
  data: reorderedData,
  lengthMenu: itemsPerPageOptions,
  columns: colNames,

  createdRow: function(row, data, dataIndex) {
 
    // This formatting applies during the row creation phase
    var daysOld = data[0]; // First column value (Days Old)

    if (daysOld == 1) {
      $(row).css('background-color', 'lightyellow');
    } else if (daysOld > 1) {
      $(row).css('background-color', 'lightcoral');
    }
  },


  // Add a drawCallback function to apply additional formatting
  drawCallback: function() {
    var table = $(myTable).DataTable();

    // Iterate through all rows to ensure formatting applies
    table.rows().every(function(rowIdx, tableLoop, rowLoop) {
      var data = this.data();
      var row = this.node();

      var daysOld = data[0]; // Get the value of the first column

      if (daysOld == 1) {
        $(row).css('background-color', 'lightyellow');
      } else if (daysOld > 1) {
        $(row).css('background-color', 'lightcoral');
      }
    });
  }
});

or target the specific cell in the first column rather than the row.

$(myTable).DataTable({
  data: reorderedData,
  lengthMenu: itemsPerPageOptions,
  columns: colNames,

  createdRow: function(row, data, dataIndex) {
    var daysOld = data[0]; // First column value (Days Old)

    // Apply background color to the first column (specific cell)
    var firstCell = $('td', row).eq(0); // Target the first column

    if (daysOld == 1) {
      $(row).css('background-color', 'lightyellow'); // Entire row
      firstCell.css('background-color', 'lightyellow'); // First column
    } else if (daysOld > 1) {
      $(row).css('background-color', 'lightcoral'); // Entire row
      firstCell.css('background-color', 'lightcoral'); // First column
    }
  }
});