Extjs store insert roweditor - extjs

Question

The setup:
I have a grid with a roweditor plugin. On the toolbar I have a "add new" button to insert a new row.
The problem:
When I'm trying to add a new record my store.insert(0, rec), doesn't seems to add the record on the 0 index.
My view:
Ext.define("app.view.partners.Partners",{
extend: "Ext.grid.Panel",
alias: 'widget.partners',
requires: [
"Admin.view.partners.PartnersController",
"Admin.view.partners.PartnersModel"
],
height: 700,
controller: "partners",
viewModel: {
type: "partners"
},
bind: {
store: '{partners}'
},
title: "Partners List",
columns: [
{ header: 'id', dataIndex: 'id', hidden: true},
{ header: 'Partner', dataIndex: 'Partner', flex: 3,
editor: {
xtype: 'textfield',
allowBlank: false
}
}
],
tbar: [{
text: 'Add record',
iconCls: 'fa fa-plus-square green',
handler: 'onAddClick'
}],
selType: 'rowmodel',
plugins: [{
ptype: 'rowediting',
clicksToMoveEditor: 1,
pluginId: 'partnersRowEditingPlugin',
autoCancel: false,
listeners: {
edit: 'onEditClick',
canceledit: function(rowEditing, context) {
// Canceling editing of a locally added, unsaved record: remove it
if (context.record.phantom) {
context.store.remove(context.record);
}
}
}
},{ptype: 'bufferedrenderer'},
{ptype: 'gridfilters'}
]
});
My viewmodel:
Ext.define('app.view.partners.PartnersModel', {
extend: 'Ext.app.ViewModel',
alias: 'viewmodel.partners',
stores: {
partners:{
model: 'app.model.Partners',
storeId: 'partners',
autoLoad: true,
sorters: [{
property: 'id',
direction: 'DESC'
}],
proxy:{
type: 'ajax',
// load remote data using HTTP
url: 'read.php',
reader: {
type: 'json',
idProperty: 'id',
rootProperty: 'data',
totalProperty:'total'
}
}
}
}
});
and in the viewcontroller:
onAddClick: function(){
var rec = new app.view.partners.PartnersModel({});
//var rec = new new Admin.model.Partners({});
this.isNewRecord = true;
var store = this.getView().getStore();
store.insert(0, rec);
this.getView().getPlugin(controllerName + 'RowEditingPlugin').startEdit(0,0);
}
here is a console.log after store.insert(0,rec)
It appears that the store does the insert, but it is inserted last. I can see it added on the grid as the last record.
I don't know what I am doing wrong.