I should note that in alsamixer, the headphone slider is always disabled, even when the heaphones are plugged in. To be more precise:
Before headphones are plugged in: Headphone slider: disabled Speaker volume: N% (say, 75%)
After headphones are plugged in: Headphone slider: disabled Speaker volume: 0%.
As the original reporter mentioned, it happens regardless of whether or not the AutoMute feature is enabled or disabled.
I should note that in alsamixer, the headphone slider is always disabled, even when the heaphones are plugged in. To be more precise:
Before headphones are plugged in:
Headphone slider: disabled
Speaker volume: N% (say, 75%)
After headphones are plugged in:
Headphone slider: disabled
Speaker volume: 0%.
As the original reporter mentioned, it happens regardless of whether or not the AutoMute feature is enabled or disabled.