Slitherine

In the attached savegame you can destroy the Necron-city but when you move a Tankbustas to 5, 34 it still cannot attack the Canoptek Scarabs despite there's clear sight. So I suppose they think the city is still there blocking sight.
I guess this just needs to run some line-of-sight-update routine as probably only happens when turns change.

Outposts are not refreshed too under our feets, we must quit and retake them after the destruction of their city.