The problem could be the Luba or the App when you encounter such an issue. Please try the following steps first.
1. Power off Luba, unplug the Key and plug it back in, then power on Luba.
2. Restart the App and try again.
Please refer to the following steps to make further check if the steps above could not solve this issue.
1. Open Settings > Bluetooth settings.
2. Power on Luba.
3. Then check if you can find a connection name with Luba.
We need to use the third-party tool to check the Bluetooth connection from Luba.
1. Open Appstore and search "BLE Scanner". Or you can click the image below to get it.
2. Open BLE Scanner.
3. Open Menu > Fliter.
4. Input Luba and enable the option.
5. Go back to the BLE Scanner panel.
6. Check if you can find the connection named with Luba.
There should be no issue with Luba if you can find the Bluetooth connection that is named with Luba with the steps above.
If the problem persists, please use the external USB Log-feedback Tool to send us feedback and send us an email to support@mammotion.com, we'll make a further check.