Try to use setTimeout with let say 100or 200 ms

Regards

jQuery('#tbl').jqGrid('navGrid','#tbl_pager',
        {
            edit:false,add:true,del:false,
            
            afterRefresh: function()
            {
                $('#tbl').jqGrid('setSelection','30'); //The row with id=30 is on first page of table defore and after refresh.
            }
        },
        {},{},{},{},{}
    )

After refresh i check id of selected row with $('#tbl').jqGrid('getGridParam','selrow') - it's correct = 30, but not highlights.
If i use $('#tbl').jqGrid('setSelection','30') in another section of code (for example in onSelectRow) and without refresh, it works correct.