Current with latest updates Fri May 26 22:40:13 UTC 2017

...But this problem actually started with the 4.9.29 kernel updates.
On fresh boot, /usr/sbin/acpid is running. After an unknown period of time and unknown event, acpid stops running, and I am forced to have root issue "acpid" in order to suspend by closing laptop lid.
Of note, no KDE, XFCE or other DE, just xmonad.
I use a simple script in /etc/acpi/events/ to control this. Those files have not changed.
Something is making acpid die, but I don't know how to find out what.

Maybe dmesg acpid?

Anything in the dmesg log helpful?

Acpid should run in the background after boot up so it sounds like something is killing the acpid daemon. Have a look at the configuration file and see if the strings and arguments seem like they are all still in check.

https://www.systutorials.com/docs/linux/man/8-acpid/

Check the configuration.
http://www.thinkwiki.org/wiki/How_to_configure_acpid

If all else fails;look up some of the debugging tools and run them.
http://www.thegeekstuff.com/2011/12/...nitoring-tools

Maybe acpid is switched off in the kernel? <not sure> OR maybe the kernel is recieving an interupt?
https://01.org/linux-acpi/documentat...ux-acpi-issues

See what cat /proc/acpi/event returns.

https://sourceforge.net/p/acpid/bugs/12/

https://wiki.archlinux.org/index.php/acpid

Hope that helps.