We have a working 4.1.3 ItemSelector in a form which submits properly. After upgrading to 4.2.1 the values are no longer submitted on form submit. In debugging we see values using both getValue() and getSubmitValue. We have not found any documentation about this.
The following is our 4.1.3 code that lives in a form (the only difference in 4.2.1 version was that we removed queryMode as we did not see it referenced anymore in th docs):
{
xtype: 'itemselector',
id: 'history_measures_itemselector',
itemId: 'history_measures_itemselector',
hidden: true,
fieldLabel: 'Information Measures',
width: 350,
height: 200,
store: form.historyStore,
queryMode: 'local',
displayField: 'Name',
valueField: 'Id'
},