I was reading this thread with interest because I’m having exactly the same problem with my Panasonic tv - (volume controlled by the now tv remote, but power not controlled).
I wonder if if you could kindly share how you got yours working in the end?
When you go into the stick menu settings under remote, pair remote, did you keep selecting that the sound doesn't stop playing option on screen until a new page appears when you are given a choice to enter your television manufacturers brand name ?
If you got to this stage and selected Panasonic, you may have to re cycle through all the sound playing prompts on screen until you accidentally find the code that matches your Panasonic TV.
I have a Panasonic TV and both my nowtv 4K smart box and nowtv smart stick remote controllers work with regards to switching on/ off the television in standby mode and adjusting the volume on the TV set.
I have indeed tried both those steps. After entering panasonic I cycled through and tried every option until I'm informed that "now tv remote may not work with your TV". Several of the options allow control of the volume, but none of them control the power of the TV. Very strange.
Don't know what else to suggest to be honest, where there is always the small possibility that the nowtv smart remote doesn't have the on & off standby codes of your television.
Perhaps if you post the model number of your Panasonic TV, then maybe if somebody owns the same television who are using the newer nowtv smart remote can confirm if they have had any success with the on / off TV standby button on the remote.
Thanks for trying to help. I contacted customer support and since they couldn't get this working, so they sent me a new stick.
The new device arrived and had exactly the same problem! After doing some digging around on the manufacturer website I eventually found a fix here:
Hope this helps someone. (The TV is a Panasonic TX-40CS520B )