Hi Matthias, since you are using LAG, the Mcast traffic might be using both links. Therefore, to accomplish the active/active VRRP scenario, the VRRP mcast address should be blocked on both ports (ISC link).
You can see any hit in the ACL by adding a counter into the ACL policy.
Example:
entry vrrp-block-rule {
if {
destination-address 224.0.0.18/32 ;
} then {
deny ;
counter matchvrrp;
}
}
To check the counter:
show access-list counter (if the ACL is applied on ingress direction)
show access-list counter egress (if the ACL is applied on egress direction)