Why does my Windows 10 Laptop fail to hibernate sometimes?

After I click 'Hibernate', my laptop does hibernate, but only sometimes. Other times, the screen immediately fades black. But then the power button stays illuminated, and 10 s later (after I clicked 'Hibernate') the screen reappears, with everything before still opened.In both cases, my laptop had the same 3 USB devices plugged.

Disabling Wake Timers and seeking the Wake Source didn't help:

Update on 28 July 2018

Performing the steps in this answer, didn't help. See this for my most updated energy-report.html.