[bug in 7.16&7.17] ipv6 nd prefix default Configuration does not take effect

it seems that “valid lifetime, preferred lifetime” does not take effect in routeros 7.16 and 7.17.
when the IPv6 prefix of the lan changed dynamically, the previous IPv6 address of the client pc does not age.
routeros 7.15 just work fine.
ipv6 nd prefix defaults.JPG