Customize settings for Windows Firewall with Block all incoming connections, including those in the list of allowed apps
Transmit from the Windows system some IPv6 packets
ping -t -6 www.google.com *(or your router even)*
Notice that the packets get dropped.
Now, disable the Windows Firewall and you get responses.
A bug in Microsoft Windows 7 & 10 code it would appear.
Using IPv4 everything works fine.
Anyone else seen this too?