keepalived nopreempt doesn't work for a virtual IPv6 address

Issue

• keepalived nopreempt doesn't work for a virtual IPv6 address. MASTER node preempts the VIP even with nopreempt parameter.

Sample /etc/keepalived/keepalived.conf:

- MASTER node
vrrp_instance TEST {
    state BACKUP
    interface enp1s0
    virtual_router_id 151
    priority 150
    nopreempt
    advert_int 1
    virtual_ipaddress {
        2001:db8:0:1::100/64 dev enp1s0
    }
}

- BACKUP node
vrrp_instance TEST {
    state BACKUP
    interface enp1s0
    virtual_router_id 151
    priority 100
    nopreempt
    advert_int 1
    virtual_ipaddress {
        2001:db8:0:1::100/64 dev enp1s0
    }
}

Refer to How to prevent keepalived vip being taken over by higher priority node when it comes back online?