Question Speakers & LG TV Connection

[HD4]

I have F&D T60 tower speakers and LG TV 4K Smart TV. When I connect my TV with the speakers via Toslink optical cable, only right speaker works. No sound in left. If I connect it via Bluetooth, even then one speaker works. But one I connect my iPhone to speakers via Bluetooth, both the speakers work.

Is there any way I can make both the speakers work when connected to the LG TV.