I don't use the private listening mode on the Roku Remote Control App, but i have just tried it out on my NowTV 4K smart box and it sort of works for me, where the sound plays into my smartphone headphones fine.
The only difficultly i am experiencing with the Roku App is that the only way i can get sound back to my TV is to reboot the NowTV box which doesn't seem right to me (pressing the headphones symbol on the Roku App again doesn't revert the sound back to my television).
Would have thought the NowTV Stick would work with the Roku App.
The only things i could suggest is make sure you are on the same WiFi home network has your smartphone or tablet where the stick can be selected to work over both 2.4 & 5ghz if you are using a dual band router.
Make sure both your mobile device with the Roku App and stick are either both on 2.4ghz or 5ghz otherwise they won't communicate with each other.
Hi, @SueDeNimes I’ve just tried using the Roku app on my iPad to control my NowTV streaming stick, and I can conform that not only does it control the stick, but private listening mode works (although it is slightly out of sync). The NowTV stick is identified as “Roku Device <serial number>”, where <serial number> is the serial number of the stick found by settings/sytem/about. Of course, only the basic controls work, including voice input, and not the four app specific buttons at the bottom of the remote.