pfSense

When the WAN interface gets a DHCPv6 and a SLAAC address it will only show one or the other pretty much at random for which one shows up. If the interface bounces it might show the same one as before or it might flip to show the other, ie if it shows DHCPv6 first then after an interface bounce/change/etc. it might still show DHCPv6 or it might flip to the SLAAC address. When looking at the CLI you can clearly see both however but the GUI only reflects one or the other when it should show both. I've noticed this issue in at least 23.09 and the 24.03 beta and I'm sure this probably impacts non-Plus versions as well.

Additionally this also causes issues for IPSec identifiers where, when using WAN IP address as the identifier, will be tied to what the GUI shows for the WAN IP address as well meaning if you have a SLAAC and DHCPv6 WAN address and something causes an interface bounce and the WAN IP "changes" then the local identifier will change too which can cause issues for IPSec tunnels.

[24.03-BETA][admin@firewall]/root: ifconfig
ix0: flags=1008843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500
        description: WAN
        options=48138b8<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU,VLAN_HWCSUM,WOL_UCAST,WOL_MCAST,WOL_MAGIC,VLAN_HWFILTER,HWSTATS,MEXTPG>
        ether xx:xx:xx:56:41:40
        inet xx.xx.xx.206 netmask 0xfffffc00 broadcast xx.xx.xx.255
        inet6 fe80::xxxx:xxxx:fe56:4140%ix0 prefixlen 64 scopeid 0x1
        inet6 2001:1111:1111:xxx::48 prefixlen 128 pltime 3600 vltime 3600
        inet6 2001:1111:1111:xxx:xxxx:xxxx:fe56:4140 prefixlen 64 autoconf pltime 3600 vltime 3600
        media: Ethernet 5000Base-T (5000Base-T <full-duplex,rxpause,txpause>)
        status: active
        nd6 options=23<PERFORMNUD,ACCEPT_RTADV,AUTO_LINKLOCAL>