For some reason, hidpp20 device names were badly set (e.g. 'Wireless Mouse MWireless' instead of 'Wireless Mouse MX Master'). Adding a 100ms delay to addDevice seems to have fixed it.
For some reason, hidpp20 device names were badly set (e.g. 'Wireless Mouse MWireless' instead of 'Wireless Mouse MX Master'). Adding a 100ms delay to addDevice seems to have fixed it.