ubuntustudio-controls and studio-controls in seeming catch-22

Question

I installed Ubuntu studio 20.4 using Ubuntu Studio Installer on a fresh Ubuntu 20.04.2 system. Everything seemed fine, but at my next apt update/apt upgradecycle ubuntustudio-controls had been kept back. I tried installing it through apt, but found

The following packages have unmet dependencies:
 ubuntustudio-controls : Depends: studio-controls but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

apt install -f gave the same result, and installing studio controls first made no difference at all.

I thought that ubuntustudio-controls was a replacement for studio-controls, but now I'm unable to install ubuntustudio controls, from a conflict that I can't seem to escape. This all happened today; the fresh 20.04.2 install was from USB .iso file.

Addendum:

[~] apt-cache policy ubuntustudio-controls studio-controls
ubuntustudio-controls:
  Installed: (none)
  Candidate: 1.13~ubuntu20.04.1
  Version table:
     1.13~ubuntu20.04.1 500
        500 http://ppa.launchpad.net/ubuntustudio-ppa/backports/ubuntu focal/main amd64 Packages
        500 http://ppa.launchpad.net/ubuntustudio-ppa/backports/ubuntu focal/main i386 Packages
     1.12.6~20.04.1 500
        500 http://sg.archive.ubuntu.com/ubuntu focal-updates/universe amd64 Packages
        500 http://sg.archive.ubuntu.com/ubuntu focal-updates/universe i386 Packages
        100 /var/lib/dpkg/status
     1.12.4 500
        500 http://sg.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
        500 http://sg.archive.ubuntu.com/ubuntu focal/universe i386 Packages
studio-controls:
  Installed: (none)
  Candidate: 2.1.64-really2.1.4-0ubuntu20.04.2
  Version table:
     2.1.64-really2.1.4-0ubuntu20.04.2 500
        500 http://ppa.launchpad.net/ubuntustudio-ppa/backports/ubuntu focal/main amd64 Packages
        500 http://ppa.launchpad.net/ubuntustudio-ppa/backports/ubuntu focal/main i386 Packages
        100 /var/lib/dpkg/status

Answer 1

EDIT: With the added info you posted, it seems you added backports ppa during the ubuntustudio-installer run to stay current with the latest packages. If you are ok without that (at least to begin with, and it is most likely enough), try removing that ppa, and installing again. In the worst case scenario, there is a mismatch in packages/versions between what is available among the different repos. Further tinkering could clarify this.

---

This is certainly strange, as I could not locate package studio-controls in my 20.04.1 apt-cache:

$ apt-cache depends ubuntustudio-installer 
ubuntustudio-installer
  Depends: tcl
    tcl:i386
  Depends: tk
    tk:i386
  Depends: debconf
  Depends: policykit-1
    policykit-1:i386
  Depends: ubuntustudio-controls
  Depends: software-properties-common

$ apt-cache depends ubuntustudio-controls
ubuntustudio-controls
  Depends: a2jmidid
  Depends: jackd2
  Depends: pulseaudio-module-jack
  Depends: python3-dbus
  Depends: python3-gi
  Depends: python3
  Depends: python3-jack-client
  Depends: zita-ajbridge
  Depends: qasmixer
  Depends: pavucontrol
  Conflicts: <cadence>
  Suggests: carla

$ apt-cache search controls | grep studio
ubuntustudio-controls - Ubuntu Studio Controls

As per this, it appears studio-controls it is available only for groovy (20.10) and hirsute (21.04).

Please post the version of packages and other info via the verbatim output of

$ dpkg -l | grep ubuntu | grep studio
$ dpkg -l | grep controls | grep studio
$ apt-cache policy ubuntustudio-controls studio-controls
$ uname -a
$ apt-cache depends ubuntustudio-installer 
$ apt-cache depends ubuntustudio-controls
$ apt-cache search controls | grep studio

Did you add any ppa?