I purchased a S90FAFXZA TV last week and it will not open last app when starting TV.  I have worked with the text chat people and they said it must not be used in this model.  I have reset the Smart Hub and reset back to factory then reset everything.  It has two options that i have turned off, 'Start with Smart Hub' and 'Autorun Samsung TV Plus'.  It is hard for me to believe that this TV would not start on previously open app, this option works on my 6 year old Q9fNA.