I have this same behavior with 3.2.2 and 3.3.0.
is navCtrl is request scoped?
And sorry but not understand clearly.. Do you clicking the menu button or the menu group?
navCtrl is session scoped.
I'm clicking the panelMenuGroup. In my case the panelMenuGroups do not have any panelMenuItems underneath it. In the future they may, but not at this time.