lazyLoad with promise not calling postProcess

[beaver71]

I'm trying to lazyloading children nodes following this tutorial:

https://github.com/mar10/fancytree/wiki/TutorialLoadData#use-a-deferred-promise

I've tried both with $.Deferred() and ES6 Promise, but when promise is resolved no postProcess function is called.
Instead using Ajax requests the behaviour is correct.

Here are examples of my code:

lazyLoad: function(event, data) {
	var path = data.node.data.path;
	// 1) Ajax is working correctly
	data.result = {
		url: "/api/listDirsRec?path="+path,
	}; 
	// 2) $.Deferred not working
	var defer = new $.Deferred();
	data.result = defer.promise();
	files.listDirsRec(path, function(resp) {
		defer.resolve(resp);
	});
	// 3) ES6 Promise not working
	data.result = new Promise(function(resolve, reject) {
		files.listDirsRec(path, function(resp) {
			resolve(resp);
		});
	});
},
postProcess: function(event, data) {
	// never called after lazy load
},