On my MacBookPro 2017 I was using a wireless keyboard and a magic mouse 2. I didn't used the wireless devices for a week, and now apple's wireless keyboard works well, but the magic mouse is not being discovered by the mac. BT works as the keyboard works, I charged the mouse many times, but as the Apple removed led indicators it is hard to say if it was chargin or it is on. I removed the device from the BT list to discover it again, but that didn't help. I use Mojave 10.14.2
There could be several issues:
- Make sure your device is turned on
The Magic Mouse and Magic Mouse 2 have a slide switch on the bottom of the device. Slide the switch to turn on the device. On the Magic Mouse, the green LED briefly lights up. On the Magic Mouse 2, green coloring is visible beneath the switch.
- Make sure your devices are setup with your Mac
If you charge your mouse wiring a lightning cable then you can go to Bluetooth preferences to see the charge level.
- Turn Bluetooth on
Go to the Apple menu -> System preferences and then Bluetooth on.