FixedColumns not working with AJAX source and disabled serverSide

Hi,

we are using AJAX source with disabled serverSide processing (so the search filtering and sorting remains fully on client). With this setting the fixedColumns is not working. As soon as we set serverSide to true it works. Is it possible to make it working without serverSide processing?

$('#stats_table').DataTable( {
    dom: 'frtip',
    ajax: {
      url: serverurl,
      type: "POST",
      data: function(d) {
        prepareStatsTablePostData(d);
      },
      dataSrc: function (d) {
        return d
      }
    },
    responsive:     false,
    paging:         false,
    autoWidth:      true,
    searching:      true,
    processing:     true,
    fixedColumns:   true,
    deferRender:    true,
    scrollY:        400,
    scrollX:        true,
    scrollCollapse: true,
    serverSide:     false,
    info: false,
    columnDefs: [...],
  });

Thank you,

Jan