Paired Apple Watch never appears in Xcode 27 / devicectl, so the Developer Mode toggle never shows on the watch

My paired Apple Watch never shows up in Xcode, so the Developer Mode toggle never appears on the watch (Settings > Privacy & Security). The paired iPhone works perfectly, and I build and install to it every day.

Setup

• Mac: macOS Tahoe 26.6, Xcode 27.0 (watchOS 27 SDK and platform installed)
• iPhone 15 Pro Max, Developer Mode ON, shows as connected in xcrun devicectl list devices over USB
• Apple Watch on watchOS 26.x, passcode set, unlocked, on wrist
• Free personal team (also tried a second free Apple ID; both are signed in to Xcode)

Symptom

• xcrun devicectl list devices lists the iPhone and an iPad, never the watch
• Devices and Simulators shows no watch under the iPhone
• No ~/Library/Developer/Xcode/watchOS DeviceSupport folder has ever been created
• Unified log on the Mac shows no CoreDevice / remotepairing activity for the watch at all. It looks like the Mac never hears from it.

Network
No router. The Mac gets internet from an iPad over USB and re-shares it over Wi-Fi (macOS Internet Sharing). iPhone and watch are joined to that network. I also tried the Mac and phone on the iPhone's Personal Hotspot. VPN is off and the firewall is off.

Already tried, no change

1. Unpaired the watch and paired again (restored from backup)
2. iPhone: Settings > Developer > Clear Trusted Computers, re-trusted, xcrun devicectl manage pair
3. Accepted the "Trust this computer" prompt on the watch after a restart
4. iPhone Developer Mode off, restart, on, restart
5. Signed out of and back in to Xcode accounts; accepted the latest agreements
6. Restarted the Mac, iPhone and watch; waited 5+ minutes with the Devices window open each time
7. Bluetooth and Wi-Fi on everywhere; watch and Mac on the same Wi-Fi

Is there a way to force Xcode to discover the watch through the iPhone, or a log predicate that shows why the watch is never offered? Any pointers appreciated.