Radvd does not start on startup (empty config file)

[bkraptor]

I have rebooted my box and then noticed that radvd was not running because of this empty config file:

[2.1-BETA0][root@box]/root(1): cat /var/etc/radvd.conf 
# Automatically Generated, do not edit
[2.1-BETA0][root@box]/root(2):

After re-saving the LAN interface without changing anything:

[2.1-BETA0][root@box]/root(2): cat /var/etc/radvd.conf
# Automatically Generated, do not edit
# Generated for DHCPv6 Server lan
interface em0 {
        AdvSendAdvert on;
        MinRtrAdvInterval 5;
        MaxRtrAdvInterval 20;
        AdvLinkMTU 1280;
        AdvDefaultPreference medium;
        prefix x:y:1014:215:0:0:0:0/64 {
                DeprecatePrefix on;
                AdvOnLink on;
                AdvAutonomous on;
                AdvRouterAddr on;
        };
        route ::/0 {
                RemoveRoute on;
        };
        RDNSS x:y:1014:215:222:4dff:fe6b:73fc { };
        DNSSL localdomain { };
};

I am running:
2.1-BETA0 (i386)
built on Tue Sep 4 16:39:17 EDT 2012
FreeBSD 8.3-RELEASE-p4

Normally I would have said the problem was with this build, but I have just upgraded from an August 23rd build that had the same issue.