I did a sudo apt upgrade on Ubuntu 21.04 on September 9th/10th and now sound no longer comes out my headphones. If I do the sound test with my headphones plugged in, it comes out the last output device, even though I have my headphones selected.
uname -r:
5.11.0-34-generic
less /var/log/apt/history.log
Start-Date: 2021-09-09 07:12:38
Commandline: apt upgrade
Requested-By: justin (1000)
Install: linux-modules-extra-5.11.0-34-generic:amd64 (5.11.0-34.36, automatic), linux-image-5.11.0-34-generic:amd64 (5.11.0-34.36, automatic), linux-headers-5.11.0-34-generic:amd64 (5.11.0-34.36, automatic), linux-modules-5.11.0-34-generic:amd64 (5.11.0-34.36, automatic), linux-headers-5.11.0-34:amd64 (5.11.0-34.36, automatic)
Upgrade: libqt5webengine-data:amd64 (5.15.3+dfsg-5, 5.15.3+dfsg-5ubuntu1), libvirt-daemon-config-nwfilter:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), linux-headers-generic:amd64 (5.11.0.31.33, 5.11.0.34.36), libvirt-daemon:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), libvirt-daemon-system-systemd:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), libqt5webenginewidgets5:amd64 (5.15.3+dfsg-5, 5.15.3+dfsg-5ubuntu1), sssd-proxy:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), sssd-ad-common:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), sssd-ipa:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), libvirt-daemon-driver-storage-zfs:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), linux-generic:amd64 (5.11.0.31.33, 5.11.0.34.36), libvirt0:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), libipa-hbac0:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), sssd-dbus:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), qml-module-qtwebengine:amd64 (5.15.3+dfsg-5, 5.15.3+dfsg-5ubuntu1), sssd-krb5-common:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), libvirt-daemon-driver-qemu:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), libsss-nss-idmap0:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), libqt5webengine5:amd64 (5.15.3+dfsg-5, 5.15.3+dfsg-5ubuntu1), libvirt-clients:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), linux-image-generic:amd64 (5.11.0.31.33, 5.11.0.34.36), libvirt-daemon-config-network:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), python3-sss:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), brave-browser:amd64 (1.29.77, 1.29.79), sssd:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), cpio:amd64 (2.13+dfsg-4, 2.13+dfsg-4ubuntu0.3), libqt5webenginecore5:amd64 (5.15.3+dfsg-5, 5.15.3+dfsg-5ubuntu1), libnss-sss:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), sssd-krb5:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), libvirt-daemon-system:amd64 (7.0.0-2ubuntu2, 7.0.0-2ubuntu2.1), thermald:amd64 (2.4.3-1ubuntu1, 2.4.3-1ubuntu2), sssd-tools:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), libsss-idmap0:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), libgd3:amd64 (2.3.0-2, 2.3.0-2ubuntu0.1), sssd-ad:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), sssd-common:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), libpam-sss:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), sssd-ldap:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), libsss-certmap0:amd64 (2.4.0-1ubuntu6, 2.4.0-1ubuntu6.1), signal-desktop:amd64 (5.16.0, 5.17.0), linux-libc-dev:amd64 (5.11.0-31.33, 5.11.0-34.36)
End-Date: 2021-09-09 07:16:07
Start-Date: 2021-09-09 07:16:19
Commandline: apt autoremove
Requested-By: justin (1000)
Remove: linux-modules-extra-5.11.0-25-generic:amd64 (5.11.0-25.27), linux-image-5.11.0-25-generic:amd64 (5.11.0-25.27), linux-headers-5.11.0-25:amd64 (5.11.0-25.27), linux-headers-5.11.0-25-generic:amd64 (5.11.0-25.27), linux-modules-5.11.0-25-generic:amd64 (5.11.0-25.27)
End-Date: 2021-09-09 07:16:29
Start-Date: 2021-09-10 07:15:36
Commandline: apt upgrade
Requested-By: justin (1000)
Upgrade: firefox-locale-en:amd64 (91.0.2+build1-0ubuntu0.21.04.1, 92.0+build3-0ubuntu0.21.04.1), gnome-control-center-faces:amd64 (1:3.38.5-1ubuntu1, 1:3.38.5-1ubuntu2), alsa-ucm-conf:amd64 (1.2.4-2ubuntu1.2, 1.2.4-2ubuntu1.3), firefox:amd64 (91.0.2+build1-0ubuntu0.21.04.1, 92.0+build3-0ubuntu0.21.04.1), gnome-control-center-data:amd64 (1:3.38.5-1ubuntu1, 1:3.38.5-1ubuntu2), gnome-control-center:amd64 (1:3.38.5-1ubuntu1, 1:3.38.5-1ubuntu2)
End-Date: 2021-09-10 07:15:43
The updates to the gnome-control-center seem like a likely candidate.
