Hi Pamalot, the Playbar reads IR for the volume controls, so you'll need to see if your Roku remote is capable of sending volume signals over IR. If you have a model number or other details about the remote, we can check it out here.
There's a thread
here with a similar question, it may be for the same version of Roku.
Fascinating. Would be nice to know exactly what pressing the purple button actually does.
If you’re still having issues, this link from Sonos Support should help to clarify:
https://support.sonos.com/s/article/3402?language=en_US
