Packet capture does not support 6rd tunnels
Only the WAN interface is shown in the interface selection box, no sign of WAN_STF.
The capture log is empty after selecting "WAN" and "IPv6 Only" as filters. The WAN interface appears to select my PPPOE connection only, as evidenced by the pfsense command:
/usr/sbin/tcpdump -i pppoe0 -p -c 100 -s 0 -w /root/packetcapture.cap ip6
When I run a modified command directly from the shell interface with the correct interface, I get results
/usr/sbin/tcpdump -i wan_stf -p -c 100 -s 0 -w /root/packetcapture.cap ip6