zabbix_agentd []: cannot create Semaphore: [] Function not implemented

Set jail_sysvipc_allow="YES" in rc.conf on the host:

# echo 'jail_sysvipc_allow="YES"' >> /etc/rc.conf

In order to change this setting on a running jail, find the jail ID with jls, then on host run:

# jail -m jid=1 allow.sysvipc=1