This should be a temporary workaround for you.....just go to the main QoS page with the bandwidth settings and just hit save without changing anything. If you then look in the syslog, you should have two messages from qos saying it found the ipv4 and ipv6 lan addresses.
Looks like it schedules a full reboot when I do the save...followed by the missing iPv6 address retries
Dec 15 08:10:41 dnsmasq-dhcp[576]: DHCPACK(br0) 192.168.1.100 00:23:54:13:33:c9 HP-PC
Dec 15 08:14:56 HTTP login: login 'admin' successful from 192.168.1.100
Dec 15 08:15:11 rc_service: httpd 582:notify_rc reboot
Dec 15 08:15:11 radvd[934]: Exiting, sigterm or sigint received.
Dec 15 08:15:11 radvd[934]: sending stop adverts
Dec 15 08:15:11 radvd[934]: removing /var/run/radvd.pid
Dec 15 08:15:11 rc_service: dhcp6c-state 945:notify_rc start_httpd
Dec 15 08:15:11 rc_service: waiting "reboot" via httpd ...
Dec 15 08:15:12 dnsmasq[576]: read /etc/hosts - 9 addresses
Dec 15 08:15:12 dnsmasq[576]: read /etc/hosts.dnsmasq - 6 addresses
Dec 15 08:15:12 dnsmasq-dhcp[576]: read /etc/ethers - 10 addresses
Dec 15 08:15:12 dnsmasq[576]: using nameserver 8.8.8.8#53
Dec 15 08:15:12 dnsmasq[576]: using nameserver 8.8.8.4#53
Dec 15 08:15:12 dnsmasq[576]: using nameserver 2001:578:3f::30#53
Dec 15 08:15:12 dnsmasq[576]: using nameserver 2001:578:3f:1::30#53
Dec 15 08:15:12 stop_wan(): perform DHCP release
Dec 31 17:00:21 rc_service: waiting "start_firewall" via udhcpc ...
Dec 31 17:00:21 kernel: Ebtables v2.0 registered
Dec 31 17:00:21 qos: using ipv4_lan_ipaddr 192.168.1.0/24
Dec 31 17:00:21 qos: ipv6_lan_ipaddr doesn't exist, retrying
Dec 31 17:00:22 qos: ipv6_lan_ipaddr doesn't exist, retrying
Dec 31 17:00:22 rdnssd[690]: Get IPv6 address & DNS from DHCPv6
Dec 31 17:00:22 rc_service: rc 740:notify_rc start_dhcp6c
Dec 31 17:00:22 rc_service: waiting "start_firewall" via udhcpc ...
Dec 31 17:00:23 WAN Connection: WAN was restored.
Dec 31 17:00:23 dnsmasq-dhcp[537]: DHCPREQUEST(br0) 192.168.1.108 b8:3e:59:63:ea:4d
Dec 31 17:00:23 dnsmasq-dhcp[537]: DHCPACK(br0) 192.168.1.108 b8:3e:59:63:ea:4d NP-1GM35A076813
Dec 31 17:00:23 qos: ipv6_lan_ipaddr doesn't exist, retrying
Dec 31 17:00:24 qos: ipv6_lan_ipaddr doesn't exist, retrying
Dec 31 17:00:25 qos: ipv6_lan_ipaddr doesn't exist, retrying
Dec 31 17:00:26 dnsmasq-dhcp[537]: DHCPREQUEST(br0) 192.168.1.111 00:18:61:26:8f:23
Dec 31 17:00:26 dnsmasq-dhcp[537]: DHCPACK(br0) 192.168.1.111 00:18:61:26:8f:23 ooma
Dec 31 17:00:26 kernel: xt_connbytes: Forcing CT accounting to be enabled
Dec 31 17:00:27 kernel: nf_conntrack_rtsp v0.6.21 loading
Dec 31 17:00:27 kernel: nf_nat_rtsp v0.6.21 loading