Volume control from systray and keyboard buttons doesn't work

[MarioMey]

Expected behaviour

Volume slider from system tray and Volume buttons should always work.

Actual behaviour

Computer just waked up and both ways to control volume don't work. But this happens today, not always. Also, I think when I boot it, the problem will be no more.

I installed Buster some days ago and everything worked Ok. But today, this happened.

Steps to reproduce the behaviour

The problem is that I don't know how to reproduce this bug and how to debug it. I just write on #mate IRC channel if someone could help me to debug it... but it's sunday, I think they all are having fun.

When I have more information, I will write right here.

MATE general version

1.20.4

Package version

mario@debian:~$ apt-cache showpkg mate-media
Package: mate-media
Versions: 
1.20.2-1 (/var/lib/apt/lists/ftp.us.debian.org_debian_dists_buster_main_binary-amd64_Packages) (/var/lib/dpkg/status)
 Description Language: 
                 File: /var/lib/apt/lists/ftp.us.debian.org_debian_dists_buster_main_binary-amd64_Packages
                  MD5: 641725f9be913faed723c6131926ab87
 Description Language: en
                 File: /var/lib/apt/lists/ftp.us.debian.org_debian_dists_buster_main_i18n_Translation-en
                  MD5: 641725f9be913faed723c6131926ab87


Reverse Depends: 
  mate-desktop-environment,mate-media 1.20
  mate-applets,mate-media
Dependencies: 
1.20.2-1 - mate-desktop-common (2 1.18) mate-media-common (5 1.20.2-1) libatk1.0-0 (2 1.12.4) libc6 (2 2.4) libcairo-gobject2 (2 1.10.0) libcairo2 (2 1.2.4) libcanberra-gtk3-0 (2 0.25) libcanberra0 (2 0.2) libgdk-pixbuf2.0-0 (2 2.22.0) libglib2.0-0 (2 2.37.3) libgtk-3-0 (2 3.21.4) libmate-desktop-2-17 (2 1.18) libmatemixer0 (2 1.10.0) libpango-1.0-0 (2 1.14.0) libpangocairo-1.0-0 (2 1.14.0) libstartup-notification0 (2 0.2) libx11-6 (0 (null)) libxml2 (2 2.7.4) mate-media-gstreamer (3 1.9.0) mate-media-pulse (3 1.9.0) alsa-utils (0 (null)) sound-theme-freedesktop (0 (null)) mate-media-gstreamer (3 1.9.0) mate-media-pulse (3 1.9.0) 
Provides: 
1.20.2-1 - 
Reverse Provides: 

Linux Distribution

Debian Buster - Mate desktop

[MarioMey]

Oooops... suddenly, volume icon disappeared :/.

I run again mate-volume-control-applet and it appears and volume works with slider. But keyboard volume buttons still doesn't work.