sonos app

On what device?

Have you tried deleting it, and downloading a fresh copy? 

That's usually a device setting, do your other apps swap portrait and landscape? 

I have an Amazon fire hd8 (12th generation).
Yes I have deleted and reinstalled. Still the same. The only other app that doesn’t swap is my heating app. However I think that is an issue with app itself as the company are constantly developing it. 

I can't find any Sonos setting for rotation or anything app specific in Android.