I believe you are seeing that because on FreePBX Distro, Asterisk is not meant to be started with systemctl, but it will be started with fwconsole commands.
Just to show you my FreePBX Distro SNG7 output, even though Asterisk is running, systemctl is showing it as stopped.
[root@freepbx ~]# service asterisk status
● asterisk.service - LSB: Asterisk PBX
Loaded: loaded (/etc/rc.d/init.d/asterisk; bad; vendor preset: disabled)
Active: inactive (dead)
Docs: man:systemd-sysv-generator(8)
[root@freepbx ~]# ps -ef|grep safe_asterisk
root 15083 1 0 May26 ? 00:00:00 /bin/sh /usr/sbin/safe_asterisk -U asterisk -G asterisk
[root@freepbx ~]# ps -ef|grep 15083
root 15083 1 0 May26 ? 00:00:00 /bin/sh /usr/sbin/safe_asterisk -U asterisk -G asterisk
asterisk 15089 15083 0 May26 ? 00:34:37 /usr/sbin/asterisk -f -U asterisk -G asterisk -vvvg -c