When hiding an actor, why do some shadows disappear while others don't?

I have two blue prints that both use the same static mesh. I have a function in the level editor that hides both actors when I press a key. Both actors disappear just fine but only the shadow of one of them disappears, the other remains. When the actors are made visible again, the “good” actor’s shadow appears again with the actor.

Any ideas why this might be?