Ignore diacritics not working

I've installed the last version of TableFilter downloading the script on my server. It works fine (and it's a great library by the way!) but I did not manage to make the ignore_diacritics feature work.

This is the code used to include TableFilter in the page:

<script>
    var tf = new TableFilter(document.querySelector('#persontable'), {
        col_2: 'select',
        col_4: 'select',
        col_5: 'none',
        col_6: 'none',
        col_7: 'none',
        col_8: 'none',
        col_9: 'none',
        col_10: 'select',
        col_11: 'none',
        col_12: 'none',
        col_13: 'none',
        base_path: '../js/tablefilter/',
        ignore_diacritics: true,
        auto_filter: {
            delay: 500 //milliseconds
        },
        filters_row_index: 1,
        rows_counter: true,
        btn_reset: true,
        status_bar: true,
        msg_filter: 'Filtering...'
    });
    tf.init();
</script>

Unfortunately I cannot provide public links to the page as it is in a intranet portal. As additional note, the page is not HTML5 but uses an old HTML4 template with iso-8859-1 charset.

portal

TableFilter version: 0.6.79 Browser and version: Chrome 73 OS and version: Windows 10

Additional information:

Problem started happening recently, didn't happen in an older version of TableFilter: No
Problem can be reliably reproduced, doesn't happen randomly: Yes

koalyptus / TableFilter

Ignore diacritics not working #710