When connecting a Home Theatre System or speaker bar to your television using wireless sound sync, it is best if the sound system and the television turn on and off at the same time. LG 2014 sound systems can do that automatically, although you can turn this feature off.
However 2013 models can only do this when connected to the television with an optical cable. wireless sound sync can only turn the audio system off.
This is normal behaviour for 2013 models, and was improved in 2014 models