Audio issue with Raspberry Pi having LibreElec

I have recently set up the Raspberry Pi2 with LibreElec latest version.

Unfortunately I having issue with the audio not playing the 5.1 and 7.1 but just stereo.

I have a Samsung 7.1 Hometheatre system.

Here are the details of the connection.

The HDMI out from the Rpi is connected to HDMI In of the AV receiver. The HDMI out of the AV receiver is connected to HDMI IN (ARC) of the samsung TV. The TV has 3 more HDMI ports namely HDMI-CAT, HDMI-MHL and HDMI-DVI

When I play the movies from Rpi I can get the sound only on the left and right channel speakers.

Any idea whats wrong with the setup?

ua60ju7000w is the model number of the TV