Fixed in v0.56.1
So there is a bug with SteamVR and Oculus where sometimes Beast Pets will show up properly in the desktop view but inside the headset things are stuck in the Oculus loading zone (white grid). This is a rather annoying bug since it doesn't throw an error but there is a work around.
To switch back to Beast Pets, press the Oculus button (on the right controller by default) to bring up the Oculus interface and then select the Beast Pets app (or possibly just Unity app) that is currently playing, then just press the Oculus button again to hide it and things should be working normally.