iPhone keeps connecting to MBP and disabling Logitech Mouse

[Makosuke]

I'm having the most maddening problem with my 2018 MBP 15" with Big Sur:

If my wife's iPhone 11 Pro (iOS 14.2) is awake, it temporarily connects to my Mac as an anonymous Bluetooth device. That alone is weird, but it goes from weird to destructive since as long as it's connected my Bluetooth-connected Logitech MX Master 2S stops working entirely, although it shows connected.

Not just jumpy or like there's interference, the mouse is stone dead.

Here's a sample of what it looks like:

The anonymous highlighted device is the iPhone. I can right-click on the iPhone and select "Disconnect", but it immediately reconnects. It will disconnect on its own after a few seconds, but then connect again, usually without end until the phone is put to sleep. AirPods Pro continue working normally when the phone is connected.

This is 100% reproducible. My own iPhone 12 Pro doesn't do this, but if I manually connect it to the Mac I can sometimes get it to kill the mouse as well.

I have figured out absolutely no way other than completely disabling Bluetooth on the phone to prevent this. I tried removing all Bluetooth prefs on the Mac, but it continues connecting automatically. It does not appear in the phone's Bluetooth settings, so there's nothing to be done there to remove it.

If I have the phone's Bluetooth Settings page open, the phone will appear in the Mac's Bluetooth pref pane with a name and vice versa, but neither device will actually initiate a connection on its own in this situation and it doesn't interfere with the mouse.

What the heck is going on here? It's driving me absolutely nuts!

I'd love to know why certain Bluetooth connections are rendering my mouse unusable, or why my phone doesn't do the same thing, but at this point I'd settle for just a way to make it stop connecting.

I should add, this might have happened sometimes prior to upgrading to 11.0, but if so it wasn't anywhere near as consistent, just the mouse would flake out once in a while.

 

[Ruggy]

Very odd
So with the phone far away from the mac so it can't connect does it appear in the Bluetooth settings page on the mac?
I'm not sure from what you say
And when the name is there and not connected, don't you get a little 'x' next to the name which you then click on to remove it?

 

[Makosuke]

So with the phone far away from the mac so it can't connect does it appear in the Bluetooth settings page on the mac?

No. If the phone is asleep, Bluetooth on the phone is disabled, or if the phone is out of range, only the mouse and AirPods appear in the Bluetooth System Pref (or the Bluetooth menu).

It will look exactly like the screenshot above but without the item highlighted in blue.

And when the name is there and not connected, don't you get a little 'x' next to the name which you then click on to remove it?

When the "phantom" name is there and not connected, there is no X, just the "Connect" button (which does not work if I click it; it times out after a bit).

When the "phantom" name is connected, as shown in that screenshot, it does occasionally (but not always, as in that screenshot) show the X. Clicking it will disconnect the device for at most a few seconds before it will again connect itself. Right clicking and clicking "Disconnect" has the same effect.

The other condition, which is only present when the Bluetooth Settings screen is open on the iPhone (so it's looking for other devices actively), actually shows the iPhone as a named iPhone instead of a generic device with a randomly-generated address like in that screenshot. In that case it does not connect automatically, and so there is no X.

I'll add that this iPhone has never been connected intentionally to this computer, and in any case I completely reset the Mac's Bluetooth preferences and re-added the headphones and mouse, so anything that might have been unintentionally remembered due to corrupt or weird preferences is gone now.

Likewise, coming from the other direction the Mac does not appear in the iPhone's settings under "My Devices", so it's not possible to select "Forget This Device" from there.