AActor::SetNetDormancy(ENetDormancy::DORM_Awake) or AActor::FlushNetDormancy should be called on an actor before making changes to its replicated properties. Waking a dormant actor reinitializes the actor's shadow state (the state used to compare what properties have changed and need to be replicated) by copying all the current values for its replicated properties. This is also why an actor's replicated state shouldn't be changed while it is dormant, as when the actor is awoken, these changes won't be detected when comparing its properties for replication.