Attach using Process ID, process picker not working

In the past, when I have attempted to debug by attaching to a process, the "process picker" has presented me with a list of running processes to attach to.

This no longer happens - in fact, nothing appears to happen.

A workaround has been to hardcode the process ID, but this is undesirable in the long-term.

My launch.json is:

{
// Use IntelliSense to learn about possible attributes.
// Hover to view descriptions of existing attributes.
// For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
"version": "0.2.0",
"configurations": [
{
"name": "Python Debugger: Attach using Process Id",
"type": "debugpy",
"request": "attach",
"processId": "${command:pickProcess}"
},
{
"name": "Python Debugger: Current File",
"type": "debugpy",
"request": "launch",
"program": "${file}",
"console": "integratedTerminal"
}
]
}