When using permeability = 1 for colliders, the non-deflected particles will simply stop at the surface.

This is because after the first collision the particle do not have a collision response which pushes them in the other direction. The result is that the same collision point will be detected in the next collision test. If the permeability is high enough (1 or close), *all* of the max. number of collisions fail and the safety collision response is used, which just stops particles.

There needs to be a way to cancel out a specific collider or face for the current particle state, otherwise the particle will either be deflected (p < 1) or eventually be stopped due to all collisions failing.