Can't load table with custom button ajax reload using deferLoading

tapable

I did not want my datatable to load initially so I read that you can use deferLoading with a value of 0, and then creating a custom button as shown below to have it load when you press the button or use a native Datatable component that makes a new ajax call.

function buttonClickHandler(event){
  $('#testTable').DataTable().draw();
}

deferLoading works fine and prevents the table from being loaded initially. Also when I press something like sort/ordering or change the page size the server returns values and results are displayed.

However even though my custom button does make an ajax call (I checked via debugging/developer tools in chrome) it quits and no results are shown, it seems as though it has the same behaviour as deferLoading. Can someone help me?