I’m experiencing the same thing. A collision box in a blueprint set to the Collision Presets of “Trigger” now causes the FirstPersonProjectile balls to collide with that trigger box. 4.8.3
It appears the CollisionComponent is now set to the ObjectType “WorldStatic” rather than the previous “Projectile” (which doesn’t appear in the drop down now.
Changing the CollisionComponent’s “Object Type” to “PhysicsBody” seems to prevent this issue.