Each device has it's own power settings. Check them and make sure they are setup correctly and the commands that are used for on/off or powertoggle are correct.

Each harmony device has a list of commands, available in the LCD when you choose that device. They are usually labeled to match the OEM remote or at least be intuitive but not always. In some cases you have to simply try each command in device mode to see what it does.

There are 2 different button configs - Device mode and Activity mode. Each one has its own unique mapping of the hard and soft (lcd) buttons to the device commands. For a Device you are limited to commands from that device (this should mimic the OEM remote). For activities you can choose from all commands for all devices or sequences of commands from one or more devices.

Find the command you want, then map it to the button you want in the Device or Activity mode you want. If a command is missing, learn it.