The process to shutdown mythbackend via systemd was working great, however now it takes well over a minute and doesn't work when suspending/resuming. I can't seem to find any log files in /var/log/mythtv so I'm not sure where to start. Any ideas? The terminal output below is systemctl status mythbackend after running systemctl stop mythbackend.
The ExecStop setting is incorrect in your systemd setup. That run of mythshutdown only sets a scheduled wakeup time but does not shut down the backend. I recommend to remove the ExecStop from the service file. systemd by default uses a kill command that is trapped by mythtbackend and that will do an orderly shutdown.
If you want the system to wakeup again at the next recording then you should set the appropriate wakeup command in mythtv-setup. Note that the wakeup time will only be set if mythbackend itself initiates the shutdown using the shutdown command you set in mythtv-setup. If you manually issue a system shutdown the wakeup time would not be set.
mytrhshutdown is not needed to be used in the normal setup. It may be helpful in some unusual cases, but I have not found a need for it.
Thanks for the help. There was an ExecStop=/usr/bin/mythshutdown --setscheduledwakeup in my mythbackend.service file. I deleted it and uncommented the one with the propershutdown command. Works great.