Why do mass-spawned actors lose collision?

SpawnActor's CollisionHandlingOverride defaults to AlwaysSpawn ignoring overlap. With many spawns at the same point, latter ones don't initialize properly. Use AdjustIfPossibleButAlwaysSpawn or set profile post-spawn.

AlwaysSpawnIgnoreCollisions guarantees actor exists; collision must be set up afterwards. Use FActorSpawnParameters with SpawnCollisionHandlingOverride.

Force collision update?

Actor->UpdateOverlaps() / SetActorEnableCollision(true) post-spawn refreshes the world's collision tracking.

Fix: Mass-Spawned Actors Lose Collision

Quick answer: Use Spawn Actor (Deferred) with AlwaysSpawnIgnoreCollisions. Set collision profile after FinishSpawning.

Spawn 100 enemies in a tight cluster. Some have no collision. Default spawn collision handling silently skips overlapping spawns.

The Fix

BP:
  Spawn Actor From Class (Deferred)
    Class:                          BP_Enemy
    Spawn Even If Colliding:        true
    Collision Handling Override:    Always Spawn, Ignore Collisions
  Set CollisionProfile = "Pawn"
  Set Actor Enable Collision (true)
  Finish Spawning

NoFail spawn always creates actor. Post-spawn collision setup ensures world tracks the new bodies.

Verifying

100 spawns: all have collision. Without override: ~30% spawn without.

“NoFail spawn. Set collision after.”

Related Issues

For attached component collision, see attached. For SpawnActor Deferred, see deferred.

NoFail. Collision after.