Datatables AJAX.reload Callback data - datatables

Question

When using Datatables (Ver: 1.10.16), I noticed that the data in the API is not updated immediately via ajax.reload in the callback even though the site says the callback is not called until the new data has arrived and been redrawn.
Notes up front:
All the data is formatted correctly and displays in the table before and after the ajax.reload, including the new data from the reload.
If I click reload twice, the api sees the new data properly and ApplyHeaderFilters works properly.
When I say the API seeing the data properly I mean like so:
$('#dtTbl').DataTable().column('1:visible').data().unique()
The ApplyHeaderFilters is the callback on ajax.reload and uses the above JS command to get unique values from the column. The data returned from the JS command are not reflecting the new data that is returned from the reload.
This is in the Document Ready:
batchDT = $('#dtTbl').DataTable( {
deferLoading: true,
pageLength: 25,
pagingType: 'simple_numbers',
scrollx: true,
initComplete: function () {
ApplyHeaderFilters($(this).attr('id'), this.api());
},
ajax: {
url: "mysite.cfm?method=gettabledata",
type: 'POST'
},
columns: [
{ title: "Description", name: "description", data: "description"},
{ title: "Is Active", name: "isactive", data: "isactive"},
{ title: "List Item ID", name: "listitemid", data: "listitemid"},
{ title: "Name", name: "name", data: "name"},
{ title: "Table Ref ID", name: "tablerefid", data: "tablerefid", orderable: false}
]
} );
$("#reload").on('click',function(){
batchDT.ajax.reload(ApplyHeaderFilters('dtTbl', $('#dtTbl').DataTable()));
});

Answer 1

For some reason the callback was being called before the reload was completed. I fixed this by wrapping my callback function in reload in an anon function. If anyone has ideas why this would be this way comment please. I have a feeling it has something to do with closures and how they are handling the callback in the datatables library.
$("#reload").on('click',function(){
batchDT.ajax.reload(function(){
ApplyHeaderFilters('dtTbl', $('#dtTbl').DataTable());
});
});