Sonos support for the Fire HD has always been weak. The new app (80.03) is a step backwards.
I use my Fire HD 8 in landscape mode. Sonos software seems to make little or no adjustment for landscape mode. The album art has always been squeezed into a small space -- the controls are larger than they need to be, so the art gets squeezed. The new software version makes the art even smaller. Is the new version working on improving landscape mode?
I am happy to send screen shots. I am also available to test any beta of the FireOS if that is helpful.