I have had this issue for about 1 year. Even when I set the power button to hibernate it will not hibernate. When i pull my laptop out of its case if I don't manually shut down my computer gets SO hot! I had to replace my battery 2 weeks ago I believe due to this problem.
I've had this same issue. Last few months my XPS 13 9380 will seldom hibernate. When I attempt to hibernate, it returns to the logon screen after a few seconds. Sometimes after I shutdown and restart, hibernate will work a time or two, but then quits working again. Dell, please solve this issue!
Welcome the infuriating world of XPS 9xxx. This problem wasn't resolved for the year after I purchased until the motherboard failed and was replaced under warranty. The problem is gone. That is the solution.
I seemed to have resolved it now; this is what worked for me on W 10:
right click the charging indicator (bottom of task bar rhs)
power options > change when the computer sleeps (lhs) > change advanced power settings > sleep >
sleep after (choose your figures) hibernate after (add 5 minutes to both the "sleep after" figures) > click OK.
Give it a try - it works for me. No more selecting hibernate and then watching it return to the log in screen.
Well, back to cycling between hibernate and log in page again after two days.
One thing I did notice was that sometimes, after successful hibernation, then when I came out of hibernation, ALL of my previously open programmes had been shut down.
I normally have open: MS Outlook, MS Money 2005 (yes!), Firefox and Crystal Disk but they would all be closed when I came out of hibernation.
As an experiment, I closed each one in turn prior to selecting hibernation. BY closing (only) MS Outlook first, my laptop now successfully hibernates each time I try it. The other programmes are still there when I come out of hibernation.