Apple Watch notify when Iphone left behind

I own an iPhone 15 Pro and an Apple Watch Series 8 (GPS model).

The iPhone is running iOS 18.4.1, and the Apple Watch is running watchOS 11.4 (build 22T251).

On the iPhone, under the "Find My" settings:

• "Find My iPhone" is turned ON.
• "Share My Location" is also turned ON.
• Under the "Devices" tab in the Find My app, the iPhone has "Notify When Left Behind" enabled.

On the Apple Watch, within the "Find Devices" app:

• The iPhone is listed with "Notify When Left Behind" also turned ON.

All notification settings are enabled on both the iPhone and the Apple Watch.

There are no "Notify Me, Except At" locations set on either device.

Regardless of where I leave my phone, even when I walk away far enough for the Bluetooth connection between the iPhone and Apple Watch to disconnect, I do not receive any notification that my phone has been left behind.

I visited the Apple Store in Hong Kong and received great support from the team. However, I also got some information that seemed confusing or contradictory, and I’d appreciate deeper clarification.

As I understand it, the Apple Watch (GPS model, without a SIM/data plan) should not require cellular capability for this specific “Notify When Left Behind” feature to work. If the feature relies solely on the watch detecting a Bluetooth disconnection, then the hardware should be sufficient. Otherwise, it seems misleading to present the feature on devices that can’t fully support it. Ideally, the OS would detect hardware limitations and hide incompatible options, avoiding confusion (as is clearly happening in my case).

So here is what I need help clarifying:

Does the Apple Watch (GPS-only) have the ability to notify the user when it loses Bluetooth connection with the iPhone, triggering the “left behind” alert?

This is what I expected from the feature — that the Watch would notify me in real-time when it disconnects from the iPhone due to distance.

I also use AirTags for other items, but I know that "left behind" notifications for AirTags are not designed to be real-time. However, I assumed that with a Watch and iPhone, Bluetooth disconnection could serve as a real-time trigger for such alerts. Unfortunately, this has not been working in my case, and no troubleshooting has resolved it.

Appreciate your help and thank you,

Oscar Cordeiro