Nexus 6P Not Being Detected

[itai33]

I want to sync my music library with my Nexus 6P (android 6.0.1), but it doesn't get detected. I have checked detect MTP devices, and set my phone to MTP. I saw an earlier thread that said to unlock the phone before connecting, which I did, but I can only set to MTP after I connect it because of how Marshmallow works; I don't know if that matters.

[Alumni]

Make sure your phone is set to "file transfer mode", rather than the default "recharging mode". You can change this by swiping down from the notification area when connected to USB.