I am having the same issue after updating the firmware.
I found an old thread about the same problem:
http://community.wd.com/t5/My-Book-Live/My-book-live-never-sleeps/td-p/199912
I read through all 18 pages and tried everything that was suggested by different members but nothing helped so I looked into activity logs to try and find what was causing it to never sleep.
I noticed my recent log looked something like this:
Aug 25 03:20:31 MyBookLive logger: exit standby after 6
Aug 25 03:32:44 MyBookLive logger: exit standby after 128
Aug 25 04:13:15 MyBookLive logger: exit standby after 12
Aug 25 04:25:25 MyBookLive logger: exit standby after 126
Aug 25 04:45:40 MyBookLive logger: exit standby after 6
So even whilst I am asleep, with no devices on, it would not go into standby for more than a few minutes without automatically waking up again. Prior to updating firmware my device would sleep most of the day without waking up and my log looked like this:
Aug 10 09:45:56 MyBookLive logger: exit standby after 23738
Aug 11 03:00:14 MyBookLive logger: exit standby after 61453
Aug 11 18:25:55 MyBookLive logger: exit standby after 54936
Aug 12 03:00:14 MyBookLive logger: exit standby after 30254
I noticed that after every time it exited standby, there would be lots of entries mentioning “OrionClient” in one of the log files so I figured that was the culprit. I found this thread when looking into Orion:
http://community.wd.com/t5/My-Book-Live/Runaway-mediacrawler-The-Ultimate-Solution/td-p/578720
I followed the instructions to disable Mediacrawler, but it still didn’t help. However in one of the comments underneath, someone mentioned a command to stop Orion. They said that Mediacrawler is part of the Orion service, together with Miocrawler and Communicationmanager. However disabling Mediacrawler itself never worked but disabling Orion did enable the My Book Live to enter sleep mode and remain there without instantly waking back up.
After rebooting my device, Orion is re-enabled and again the My Book Live will wake up almost instantly upon entering sleep mode so it is definitely Orion causing it (in my case).
You can check your logs if you go into your My Book Live UI then go to “Support” at the side. Click “Create & Save”, under “Create and Save System report”. It will download a zip folder for you. Inside will be a “log” folder and inside that will be a “user.log” file. If you open that you should see how often it goes into standby and for how long. There should also be a “messages” and “messages.1” file inside the “log” folder. Open with a text editor and search for the world “standby” to see if you can figure out what is happening after it exits standby. For me there were lots of “OrionClient” entries. If yours is the same, try follow the disabling Mediacrawler instructions link above but use the stop Orion command in the bottom of comment 9 of that thread.
I hope WD release a fix soon since it doesn’t appear to be an isolated case and for me, it’s only temporarily fixed and was not something that could be achieved with a simple minor setting change. But hopefully that gives you a general direction to solving the issue. Although having read through the 18 pages of the first link, it appears different people have had different solutions despite the problem being the same. If only there was a way to rollback the firmware to an older version.