ExtendScript Debugger can't open debug session in Premiere

We're having a problem using ExtendScript Debugger in Visual Studio Code on one of our Macs.

With a fresh install of both Premiere, Visual Studio Code, and the ExtendScript Debugger plugin, we get this error when launching a debug session:

Can't start a session without an active target and engine. Select an active target and engine before trying again.

However, the selector for different targets is not visible. The user can't select an engine.

We've tried to workaround by specifying the target in the launch.json config file (tested on another machine):

"targetSpecifier": "premierepro-13.0",
"engineName": "main"

However, we see this message:

Target '' is not running. Select yes to launch.

After selecting 'yes', we see this error:

(#7)Unable to retrieve last error information.

We've made sure ESTK is uninstalled, tried restarting Premiere and VS Code, tried restarting the computer, and tried reinstalling Premiere and VS Code. But we still can't get VS Code to open a debug session.

Thanks in advance for your help!