"I couldn't find event logs regarding hibernation failure. Is there a report is generated somewhere else?"
Troubleshooting Windows 8.1 Sleep and Hibernate includes instructions on where to look in the event logs (see below).
You can also try the following command:
A report is written to
According to Ultimate Troubleshooting Guide for Windows 8.1 Not Going to Sleep this report will contains any errors regarding sleep/hibernation. It goes on the explain how to read the reports and fix any errors.
Source Ultimate Troubleshooting Guide for Windows 8.1 Not Going to Sleep
Generate Power Report
The power report you generate in Windows 8 or Windows 8.1 can sometimes tell you what is preventing the computer from going to sleep. I ran it and got some useful info. To run the power report, open an administrative command prompt and type in the following command:
It’ll take about a minute or so to run and after it finishes, it’ll tell you how many errors and warnings were found. Hopefully, if you’re having this sleep problem on your Windows 8.1 machine, you’ll have some errors!
In order to view the report, you have to go to C:\Windows\System32 and open the energy-report.html file in your browser. However, for some odd reason, the file would not load in any browser when I tried to open it from that directory, so I just copied the report to my desktop and then opened it and it worked fine.
Source Troubleshooting Windows 8.1 Sleep and Hibernate
When Windows 8.1 is having a problem, I am trying to train myself to begin troubleshooting by inspecting the Windows logs. At the Metro UItype "ev" and then look in "Settings".
A good place to start in the Event Viewer is with Summary of Administrative Events".
Follow-up by looking in the System Log and filtering for
Interesting items would include "The last sleep transition was
unsuccessful", or "The system is entering sleep".
Source Sleep Mode not working in Windows 8.1
Press Windows+W and type "troubleshooting" in the search box. Click on the "Troubleshooting" from the search results
In the following window, from the left hand side listed options, click on "View all".
Moving on, pick "Power" from the list so available, this would launch the Power Troubleshooter.
In the Power Troubleshooter, you have to click "Next" option:
This will start the automatic detection and fixing of issues.
- When the troubleshooting has been completed, you can click "Close".
Now you can reboot the machine, after restart, you’ll find that the
issue is already fixed.
The above source also includes screenshots (omitted for brevity).