Edit: After half day, my wife’s Mac started having the same problem. I have then applied the solution that I found in the Apple
Find My Mac Is Launched To Developers Through iCloud.com
We have been contact by a few of our readers and followers on twitter that Apple have launched the featured called Find My Mac The feature is simply Find my iPhone for the Mac, which you may have got from the name .
The user can turn the feature on in the iCloud control panel and then their Macs will show up on iCloud.com.