IPV6 auto method not working

[Jeremy Ardley <jeremy ardley org>]

I have a debian stretch system acting as a client.

I have another system acting as ipv6 router and dhcpv6 server . I am
using isc-dhcp-server and radvd router advertisements.

My issue is that the client instance of NetworkManager is not behaving
as expected

This stanza does not attempt to get an ipv6 address

[ipv6]
addr-gen-mode=eui64
dns-search=
ip6-privacy=2
may-fail=false
method=auto

This stanza gets an ipv6 address but does not get a default route
(expected to not pick up default route)

[ipv6]
addr-gen-mode=eui64
dns-search=
ip6-privacy=2
may-fail=false
method=dhcp

I also have ipv4 enabled in the connection and it works correctly

I have run wireshark on the client and see no dhcp6 related traffic when
method=auto.

version: network-manager-gnome/oldstable,now 1.4.4-1+deb9u1 amd64
[installed]