Unlock your Chromebook with your Android phone I'm using following:


Huawei Nexus 6p with Android 7.1.2 (up-to-date).
ASUS Chromebook Flip with Google Chrome OS (58.0.3027.0 dev
(32-bit)) (up-to-date).


and I'm trying to follow: Unlock your Chromebook with your Android phone - Chromebook Help, however I'm unable to complete step #7 with following message on my Chromebook:


  Failed to connect to "Nexus 6P"


yet through "Notifications", I've got another message:


  Bluetooth device "Nexus 6P" has been paired and is now available for
  all users. You may remove this setting using Settings.


Please advise.
I apologize for not posting an answer in timely manner, however I'm doing it right now (that's the best I can do); As of now I'm using Google Chrome OS / Version 66.0.3359.43 (Official Build) dev (64-bit) and Pixel, (Phone by Google (1st generation)) w/ Android 8.1.0.

I went ahead and removed my Phone from Chromebook's Bluetooth devices and from Chromebook from Phone's Bluetooth devices, now that everything is tidy widy, you can proceed to next step:

under Settings, expand Screen lock (under People), click on Smart Lock for Chromebook (beta) and follow steps.