I recently got a small HP Chromebook to use as a "sitting on the couch " internet device and loaded the Sonos app. What I've observed is that the app seems to push its volume settings to my Sonos units from its last use without first loading the current settings from the system.
e.g., I have the Chromebook, my Windows PC and my iPhone all showing the Sonos app for some room. If I change the volume from the iPhone, the volume changes and the slider updates on the PC's screen, too. But the slider on the Chromebook doesn't move! Same if I change the volume from the PC. The iPhone shows the change, but the Chromebook doesn't. Now, if I click on the Chromebook's Sonos app window, the Sonos volume immediately goes to whatever its last commanded volume was. Of course the apps on the PC and iPhone jump to that volume, as expected. This is reproduceable every time, so I conclude it's the Android/Google Play app.
I reported this by email ticket #171218-000111 but they want me to call in to help them work on it. I would do that, but recently (maybe since the introduction of the Sonos One) they report a wait time of over 30 minutes, and they don't offer a callback feature. I just dropped it, telling them that I could put up with the problem, now that I understood it until they choose to fix it.