From another post I tried this and it worked!
Not touching fail2ban, proftpd jail and filter at default.
Edit: /lib/systemd/system/proftpd.service
and replace and put in this section:
[Service]
Type=forking
Environment=PROFTPD_OPTIONS= CONFIG_FILE=/etc/proftpd.conf
EnvironmentFile=-/etc/sysconfig/proftpd
ExecStartPre=/usr/sbin/proftpd --configtest -c $CONFIG_FILE
ExecStart=/usr/sbin/proftpd -c $CONFIG_FILE $PROFTPD_OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
PIDFile=/run/proftpd/proftpd.pid
I think there is a problem where the script is not paying attention to the config file.
So with CONFIG_FILE=/etc/proftpd.conf seems to fix it for me.