This can happen if Caavo only knows how to toggle the power of your AVR/sound bar (as opposed to being able to specifically tell it to turn on or off), and Caavo gets out of sync with the state of the power. To fix this, when your TV is on, simply power the AVR/sound bar on maunally using the device front panel or original device remote. After this, your TV and AVR/sound bar should power on and off together when controlled from the Caavo remote.
To help prevent this problem in the future, you may want to use one of the included IR accessories to reduce the chance of a power command being missed. If your AVR/sound bar is connected to Caavo via HDMI, you can use the HDMI-IR adapter for this. Otherwise, you can use the TV IR accessory.
Also, if your AVR/sound bar is connected to Caavo via HDMI, try enabling HDMI-CEC on it (if your device supports it). HDMI-CEC wil enable Caavo to track the power state of the AVR/sound bar. After you have enabled it, reset, and re-configure the AVR/sound bar by going to Settings > Devices > [AVR/sound bar] and selecting "Reset Output".