Instance Checks on IPv6 only instances?

This instance has been consistently failing the instance check essentially since I created it.

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/monitoring-system-instance-status-check.html#instance-status-checks

From the link, "Amazon EC2 checks the health of the instance by sending an address resolution protocol (ARP) request to the network interface (NIC)."

It's an IPv6-only instance. There are no ARP packets seen nor would an IPv6 instance respond to ARP.

So the question is, is ARP the only instance check that's available?

I believe ICMPv6 is being used instead of ARP, but I cannot present any AWS documentation that clearly describes it.

For example, the following document refers to it as a neighbor discovery protocol but does not state that EC2 uses it. https://docs.aws.amazon.com/whitepapers/latest/ipv6-on-aws/brief-ipv6-overview.html

I'm sure you are fed up with my repeated references, but IPv6 is based on the Nitro System, so make sure you are using a supported instance type and OS.

https://docs.aws.amazon.com/ec2/latest/instancetypes/ec2-nitro-instances.html

https://docs.aws.amazon.com/vpc/latest/userguide/aws-ipv6-support.html

Not fed up at all, I appreciate the effort. When I stated in the question, "I have an IPv6 only instance which fails the instance check despite everything working just fine," I meant that the instance has full useful IPv6 connectivity -- the only complaint I have is a false alarm on the instance check. Yes, it's on a Nitro instance. The IPv6 neighbor discovery works; if I send neighbor solicitation packets, I get responses. But the EC2 infrastructure never seems to send me any neighbor solicitation packets to probe my instance's health, which is what I would expect.