Here is sharing from our colleagues about their problem with Asus Zenfone 2 Bluetooth.
This sharing can also be used to troubleshoot bluetooth problem on other Asus Zenfone devices.
I recently updated my Zenfone 2 (ze551ml) to Android 6.0.1 marshmallow. Since then my bluetooth is not working. Bluetooth remains off even if i switch it on. So I am not able to use bluetooth.
Try one of the following solutions:
1) Check if you have not performed factory reset, after update. If not do it right away, your issue might get resolved.
2)Try clearing cache of bluetooth. Go to Settings->Apps->All->Bluetooth/Bluetooth Share->Clear Cache and Data->Restart your device
3) Turn on your device in Safe Mode, to enter safe mode
->Press and hold power button
->On Popup, tap and hold, “Power off”
->You will be asked to restart in safe mode, tap Ok/Yes
->Now when you are in safe mode, Start Your Bluetooth check if it works, if yes->Pair it with some other device and try sending files.
->Keep Bluetooth on and restart your device. Your issue might get resolved.
Hope this will help you solve the Bluetooth issue.