Why can’t I use the volume buttons to control the receiver/soundbar volume in Activity mode?

If the volume commands work under Device mode but not Activity mode:

Our remote’s Activity feature supports a fully customizable button layout, so when you activate an Activity, the remote buttons can control different devices independently. Therefore, you need to reassign the corresponding commands for all buttons under the Activity.

When setting up an Activity, the app will ask you which devices you want the buttons to control. If you didn’t make the correct selections during setup, please follow the steps below to make changes:

1. On the Activities page in the app, tap the edit icon in the top-right corner (it looks like a pencil), then tap the edit icon next to the Activity you want to edit.
2. Tap Customize Remote Buttons, then select the button you want to edit.
3. Select Shortpress, Normal Keys, then select the device you want the button to control and the corresponding command.
4. Confirm, exit the settings page, wait for the remote to sync, and test it.