Fresh install of MATE 20.04 Beta1 aarch64 on a 8GB Raspberry Pi 4. Connected via HDMI to two monitors, both without sound support. Powered speakers attached using the 3.5mm audio jack. RPi is using firmware 000137ad
Running "sudo amixer cset numid=3 1" returns the error "amixer: Cannot find the given element from control default"
From the hardware tab of Sound Preferences, I see three devices (assumed HDMI1, HDMI2, 3.5mm). Using the Test Speakers button on each of the three does not output audio from the speakers. (no audio over HDMI is expected)
Audio works as expected using 2020-05-27-raspios-buster-full-armhf.
Anyone else seeing this behavior or have working 3.5mm audio output on 20.04?