Hardware: Mac mini (2024, M4), 16 GB
OS: macOS 27.0 (26A428)
Device: Magic Mouse 2, firmware 1.9.2, VID 0x004C, PID 0x0269
SUMMARY
After updating to macOS 27.0 the Magic Mouse 2 pairs and shows as
Connected with a battery level, but sends no input at all. The Mouse
pane in System Settings is empty. A Magic Keyboard on the same Mac over
the same Bluetooth stack works normally, as does a non-Apple Bluetooth
mouse. The same Magic Mouse works correctly on another Mac running
macOS 26.
STEPS TO REPRODUCE
1. Update a Mac to macOS 27.0.
2. Pair a Magic Mouse 2 (firmware 1.9.2).
3. Move the mouse.
EXPECTED
Pointer moves, clicks and gestures work, Mouse pane shows settings.
ACTUAL
No pointer movement, no clicks, no gestures. Mouse pane empty.
DIAGNOSIS
The mouse never becomes an HID device:
ioreg -c IOHIDDevice -> no Magic Mouse entry
ioreg -c IOBluetoothHIDDriver -> no instance
ioreg -c AppleMultitouchDevice -> no instance
bluetoothd flags the device on every connection:
DvF 0x40000024000 < ClassicPaired HIDBadBehavior Connectable >
CnS 0x800020 < HID ACL >, SupS 0x20 < HID >, Battery M -65%
Magic Keyboard on the same host, working:
DvF 0x40000114000 < ClassicPaired HIDGoodBehavior ConnectedOverUSB Connectable >
Telemetry in the same log: ConnectedClassicHIDDevice : 0
The reported battery level is negative (-65%) while ControlCenter, in
the same log, reports the same device correctly as batteryLevel: 0.65.
Another user reports -63% at 63% charge with identical symptoms
(discussions.apple.com/thread/256357286).
This suggests a sign error when parsing the Magic Mouse battery field,
causing the device to be classified HIDBadBehavior, which prevents the
HID profile from attaching.
ALREADY RULED OUT
Re-pairing, pairing by cable, pairing from a cleared device list,
Bluetooth reset, multiple reboots, Safe Mode, resetting
com.apple.AppleMultitouchMouse and
com.apple.driver.AppleBluetoothMultitouch.mouse preference domains.
None survive a reconnect, because the flag is recomputed each time.