TV: UN50MU6300 50" 4K Ultra HD Smart LED TV (2017 Model)
cable box: Videotron Helix arris xi6-t model:tx061aei
I recently upgraded from a standard videotron cable box to a helix cable box. I noticed today that I am unable to change the channels using my samsung remote. The setup steps do not include this cable box model.
Unfortunately, not all 3rd party accessories are supported. I would recommend checking for available updates as well as trying a factory reset.
I'm not sure if this will help with your TV model, but I have successfully paired the Samsung One Remote with the Helix box (the TV is a Samsung Frame)
First you have to choose Videotron as the provider.
Then pick Arris as the manufacturer.
And lastly enter the model number listed under the Helix box.
Unfortunately the remote uses infrared with Helix, and requires direct line of site compared to the original Helix remote that uses Bluetooth.
Hope this helps