Logitech MX Master Frequently Asked Questions Manual page 28

Reset the Mac's Bluetooth settings
WARNING: This will reset your Mac, and cause it to forget all of the Bluetooth devices you have ever
used. You will need to re-configure each device.
1. Make sure Bluetooth is enabled and that you can see the Bluetooth icon in the Mac Menu Bar at
the top of the screen. (You'll need to check the box Show Bluetooth in menu bar in the
Bluetooth preferences).