With Ubuntu 16.04 laptop doesn't suspend when lid is closed
I stumbled across an answer that seems to have worked. Too bad there is not a cleaner way to do this than to alter the default settings. Would rather the System Settings|Power setting worked.
I edited the file '/etc/systemd/logind.conf'
sudo vi /etc/systemd/logind.conf
Then I uncommented the line (removed the beginning #) containing 'HandleLidSwitchDocked=ignore' and changed the value to be:
HandleLidSwitchDocked=suspend
After a reboot all seems to be working as expected, though I'm still prompted to login twice. (Once to unlock, and again as a user of the OS.)
I had a similar problem. There is apparently a bug in the 4.4.0 kernel. The problem can be solved when you install the new kernel 4.4.8.
You can find instructions to do it here: http://linuxdaddy.com/blog/install-kernel-4-4-on-ubuntu/
Works perfect for me.
I have/had the same problem and found this link helpful. Laptop does not suspend when lid is closed
Like one of the people with "solutions", I found that I have to manually suspend my laptop initially before closing the lid on subsequent occasions will work.
Good luck with it.