I've not redefined Picker, and this happens on a blank project. What I'm seeing, is that if I type Picker( , it does not display. If I type Picker, then press RETURN, and then ( , it seems to register that I'm using Picker and gives me the INITs. I'll keep playing around with it, because that's not the behaviour I am used to.

Claude, Thank you! I think you've cracked it. I rebooted my mac, and after reboot I was sitting OK with 0 bytes of "Swap Used". If I launch the iOS simulator on it's on, the "Swap Used" rises to ~700 MB If I then launch xCode, the "Swap Used" rises up to ~1.8GB If I then launch the preview for a SwiftUI view, the "Swap Used" rises up to 2.1GB I think this is both good and bad news. Good that the issue has been figured out, but bad that my MPB does not have expandable RAM... so I would need an upgrade!