Sound coming from bothe headphones and speaker

When I plugin my headphones through the front jack in my desktop my speaker does not auto mute and sound comes from both in Leap 42.1 Gnome.

When I open the alsamixer program through terminal, I see that automute option is missing.

When I use SLED 12 SP1 the alsamixer program shows automute and is enabled, and also when I plug-in my headphones the speaker automutes, the same is true with Windows 7 and Windows 10.

btw my soundcard is Realtek AC’97.

My question is why the Automute option is missing?

Any solutions?