Just another case to confirm the same situation:
G5500+H310M+4GRAM+HDMI with version 12.0.1 (I also tested version 11), no sound is played for most videos untill I follow this thread, seting fixed+44.1 is the only way to have sound.
But another interesting thing is:
when I set GUI resolution to 1080P, both the GUI and video sound disappears even the "fixed+44.1" is set.