Navigator and collision system treat slopes in a different way
An example is Infidelities quest from Tribunal. Marked area is not walkable, despite navigator assumes that it is, so Velyna Seran stuck:
When actors stuck, it can break quests, so we need somehow either to make sure that navigator matches collisions system or add some kind behaviour to AI to work around this bug.
Note that in case of Infidelities quest this bug is masked by bug #6307 (closed) in 0.47.
The bug can probably be a some kind of precision mismatch - a normal z part in the isWalkableSlope
is 0.655944 in marked area, while it needs to be more than 0.656059 to be walkable.