@Chaosphere64Does your WAN interface get an IPv6 assigned automatically with your configuration or do you set an address manually, which is used for dpinger?
After selecting the option dpinger starts instantly while the interface has just its fe80::/10 address. After some time the interface also holds a GUA, which again is outside the delegated IPv6 prefix.
ping: bind: Can't assign requested address
https://github.com/opnsense/core/commit/287c13beb# opnsense-patch 287c13beb
inet6 fd9c:85da:835d:8696:92e2:baff:feb0:efeb prefixlen 64 detached autoconf pltime 1800 vltime 1800