Your export says
/ipv6 address
add from-pool=IPv6-pool interface=bridge
This means that you have set address=::, so the resulting address is a “subnet router anycast address”, which I believe cannot be assigned as an individual unicast address of an interface. So try changing that to the ::1 you’ve shown in the OP and try again.
If this is not the issue, the only thing to come to my mind except a mere bug is that attaching the DHCPv6 server to the bridge might prevent the router from responding to the Router Solicitation requests.