The little markers and nametags floating over the heads of units disappear in End Game spectator, when Free Camera mode is used.
According to SilentSpike of the ACE dev team:
The commands for drawing icons/lines in 3D have no visible effect when the current cameraOn unit is not alive. There's a bit of weirdness to this in that it never seems to happen in respawn modes 2/3 where the player is still associated somehow with their corpse for the duration of the respawnDelay mission attribute. However, in other respawn modes where the player dies permanently they seem to become disassociated with their corpse after a seemingly random time (some kind of engine garbage collection) which is when the icons stop drawing (I'm guessing what's actually happening is that the AI brain associated with the unit is no longer present - and yes, players have an AI brain of sorts).
That's the reason why it only fails in free camera, because behind the scenes the view is switched back to the player unit. The way I've fixed this in ACE is to have a temporary agent unit which I switch the view to while in free camera.