On 3 occassions this week, upgrading to a custom build based on 12.0 stable, the upgraded controller comes up with interface ntb0 having no carrier.
TrueNAS 12.0-U1 to custom build (seen twice)
TrueNAS 12.0-BETA2 to custom build (seen once)
In all 3 cases, passive node which was upgraded does not have carrier on interface ntb0. First two times a simple reboot of the passive fixes the issue. THird time I left it in this state for people to analyze root cause.