If the client received AttachSocketName before AttachParent, USceneComponent::AttachToComponent will be called while AttachParent may be null, resulting in the received socket name being lost. When AttachParent is then received, USceneComponent::AttachToComponent will be called without the correct socket name.
Replicated actor will be attached to the first on the specified socket.
Slight chance that the actor will not be attached on any socket.
There's no existing public thread on this issue, so head over to AnswerHub just mention UE-95611 in the post.