I saw this help request from @htilly but am too late to provide an answer.
I run Pi-hole on a Banana Pi, forwarding to OpenDNS. My router is a Ubiquiti USG, which was previously handling DNS for me.
I am in the UK and use a Hurricane Electric IPv6 tunnel, which Netflix identifies as a proxy to get around its regional restrictions. The script below worked on the USG to fix this by providing "null" answers to IPv6 AAAA requests for Netflix domains. I've now tried it on the Pi-hole — just paste it into a file (e.g. 03-pihole-netflix.conf) in /etc/dnsmasq.d and restart dnsmasq or pihole-FTL if you're running the beta.
server=/netflix.com/#
address=/netflix.com/::
server=/netflix.net/#
address=/netflix.net/::
server=/nflxext.com/#
address=/nflxext.com/::
server=/nflximg.net/#
address=/nflximg.net/::
server=/nflxvideo.net/#
address=/nflxvideo.net/::