An update has rolled out for Pokemon Go, introducing a new Nearby tracking system for a “subset of users.”
The Nearby drawer now has two sections: Nearby and Sightings.
“Nearby” Pokemon are those that are close to nearby Pokestops. Tapping one of those will zoom up the map to an overhead view, showing you the Pokestop you should head towards. Pokestops now have circles around them with similar sizing to the one around the player’s – if a Pokemon is within the circle, it counts as being “nearby” to the Pokestop.
Pokemon in the “Sightings” sections have grass behind them rather than a Pokestop image – meaning that they’re not immediately near a Pokestop, and you’ll have to hunt for them without any guidance.
If a Pokemon despawns before you find it, it’ll disappear from the Nearby drawer. A similar disappearing act will happen if you’re no longer within a reasonable distance from a Pokemon. If you’ve tapped on a Nearby Pokemon to start tracking it and it despawns, a popup will let you know it’s gone.