If a public IP is assigned to a VPC, a VM running inside that VPC cannot ping that public IP. This is due to the IPtables Nat rules set in such a way that drop any requests to the public IP from internal interfaces. I am fixing this so that internal hosts can also reach the public IP.
Reproduction:
Create a VPC
Create a network inside the VPC
Allocate a public IP
Create a VM in the network
Create a port forwarding rule enabling ICMP
ping the public IP inside the VM (this will fail)