It's so frustrating when one tries to watch a movie and the audio is out of sync with the action!!
I can see from many previous discussions that this has been and continues to be a problem for Now TV and yet there seems to be no solutions.
Personally I am not a fan of the Now TV stick, when I had and used my Roku stick I found this was a much more reliable device.
Too often it overheats and is pretty slow. I found myself unplugging it almost every night and plugging it back in on the morning.
Might be an idea to get the new Roku stick?
I've been having this issue recently. I've only noticed it on the HDMI stick that I use the most. I thought it was related to the previews they've started showing.
It's never happened on iPlayer or netflix so far as I remember. Rebooting seems to do the trick.
Also I found an option in the settings to select PCM audio output is that a recent addition? It seems to sound better because my speakers plug into the TV which won't pass through surround. Alas doesn't seem to cure the audio synch problems, I've got several other sticks so will try them.