Dolby Digital Plus sound does not output from the device connected with the optical digital cable.

This is a specification of the product.
When receiving the Dolby Digital Plus audio, the TV is designed to mute audio from the DIGITAL AUDIO (OPTICAL) OUT jack.

NOTE:

• If you wish to listen to sounds with Dolby Digital Plus, connect the HDMI ARC jacks on the TV and the output target device with an HDMI cable.
• When you use an optical digital cable to connect the devices, you can listen to sounds as Dolby Digital with the steps below.

1. Press the ACTION MENU button on the remote.
2. Select Sound adjustments in the Display & Sound category.
3. Select Advanced settings.
4. Select Dolby Digital Plus output in the Input related category.
5. Select Dolby Digital.