Sudo elevation not working with gdb

Type: Debugger

Describe the bug

• OS and Version: Ubuntu 18.04.2
• VS Code Version: 1.38.0
• C/C++ Extension Version: 0.25.1
• Other extensions you installed (and if the issue persists after disabling them):
• A clear and concise description of what the bug is.

When trying to attach with gdb it correctly asks "Superuser access is required to attach to a process. Attaching as superuser can potentially harm your computer. Do you want to continue? [y/N]". After typing "y" and enter, I get the following:

==== AUTHENTICATING FOR org.freedesktop.policykit.exec ===
Authentication is needed to run `/usr/bin/gdb' as the super user
Multiple identities can be used for authentication:
 1.  ...
 2.  ...
 ...
Choose identity to authenticate as (1-16): [1] + Stopped (tty input)        /usr/bin/pkexec "/usr/bin/gdb" --interpreter=mi --tty=${DbgTerm} 0<"/tmp/Microsoft-MIEngine-In-hrnsnxv9.sdc" 1>"/tmp/Microsoft-MIEngine-Out-prn74k9m.v7c"
You have stopped jobs.

It immediately stops and doesn't let me select an identity. It says "Running" in the debug view but this seems not correct, also nothing happens when pressing pause.

To Reproduce
Please include a code sample and launch.json configuration.

        {
            "name": "Attach",
            "type": "cppdbg",
            "request": "attach",
            "MIMode": "gdb",
            "program": "...",
            "processId": "${command:pickProcess}",
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ]
        },

Additional context
If applicable, please include logging by adding "logging": { "engineLogging": true, "trace": true, "traceResponse": true } in your launch.json
Add any other context about the problem here including log or error messages in your Debug Console or Output windows.

提供された launch.json 構成を使用し、GDB とプロセスピッカーで Ubuntu 18.04 上の attach フローを再現します。まず、レポートに示されている認証と pkexec のやり取りを調べます。アイデンティティを選択して attach が完了し、デバッグビューが正常に応答すれば完了です。