If that person was recently a ghost there is an extended timer for you to see them from the skies using where. If you did a flyby (is that scout?) you would have probably seen them in the room.
Vast majority of players will fly over the bramble pit. My plainsrunner was nexun and even so most of battle flew over my bramble pits. Even if they walk into it it only lags for a bit (it doesn't hold them). Snare will snare the whole group (assuming they walk into the room together and not send someone ahead) giving you plenty of time to get to them.
'CABAL QUESTIONS' 'CABAL ITEMS' 'ITEMS OF POWER' (1896)
The inner guardians of each cabal's Item of Power are linked to the fate of
their respective item. Through this, they are aware of its location if its
powers are seized by another cabal. Members of their cabal may ask them for
their item's location, or for which enemy items are under their guar