The default C++ project stub generated by Clickable cannot run on my Pixel 3a (20.04 Stable channel).

When I build the project with the command CLICKABLE_FRAMEWORK=ubuntu-sdk-20.04 clickable, it fails at the installation step with this message:

Installing the app.
Error: GDBus.Error:com.lomiri.click.OperationFailed: failed to install /home/phablet/appname.yourname_1.0.0_amd64.click
Command ran on device via ADB failed. See output above.

The only thing I've changed from the freshly generated stub is in the appname.apparmor file. I changed "policy_version": 16.04 to "policy_version": 20.04.

Some things I've tried:

• The pure QML, Python and HTML templates work fine. The Rust template gives the same error as the C++ template. The Go and Godot templates gave each their own unrelated error.
• Using CLICKABLE_FRAMEWORK=ubuntu-sdk-20.04 clickable versus just clickable and specifying framework: ubuntu-sdk-20.04 in clickable.yaml.
• I cleared my cache a few times ("Is it okay to delete and re-download it?" -> yes) and created a few different projects to ensure it wasn't a problem with a project in particular.
• I reinstalled the core apps on my phone through the Settings app.
• I switched to the 20.04 Development channel.

Is there something I can do to narrow down the problem? I found no other issue about this, so I'm not sure if it's a problem with my device or if it's a bug in Clickable.