I've just installed Ubuntu Mate 18.04.1 on my laptop (Asus X555UB) alongside Windows 10 (dual boot). I'm using the laptop connected to a TV via HDMI. The audio output from the TV works fine if I select "Digital Stereo (HDMI) Output" profile in the Sound Preferences, but I can't use the laptop's headphone jack nor the laptop speakers, no matter what profile I select.
If I connect the headphones, the audio (from the TV) goes mute, the Sound Preferences changes the output to Analog Stereo Output, the Port says there are headphones plugged in, but no sound comes from them.
I've also tried tinkering with Pulse Audio Volume Control and even Alsa Mixer, but have had no luck with either.