sshguard is not adding hosts to the pf table because the -T and -t command options are in incorrect order.
sshguard / src / fwalls / command_pf.h
See lines 40, 48, and 51.
Per the pfctl man page, the commands should be:
[-t table -T command [address ...]]
To replicate, try adding an ip address to the table the wrong way
pfctl -Tadd 18.104.22.168 -tsshguard
usage: pfctl [-deghnPqrvz] [-a anchor] [-D macro=value] [-F modifier] [-f file] [-i interface] [-K host | network] [-k host | network | label | id] [-L statefile] [-o level] [-p device] [-S statefile] [-s modifier [-R id]] [-t table -T command [address ...]] [-x level]
Then try the right way
pfctl -tsshguard -Tadd 22.214.171.124
1/1 addresses added.