I know this is an old post, but since google leads to this answer quite often I thought it might be useful to answer here.
In CharacterMovementComponent::TickCharacterPose(float DeltaTime), you will see that it manually ticks the pose of the character mesh, based on its own networking updates. In addition, under ACharacter::PossessedBy(AController* NewController), it sets Mesh->bOnlyAllowAutonomousTickPose as true. So the listen server will see the animation bp tick at the same rate as the server tickrate. You will need to edit the engine code to disable this behavior, and I don’t know if it will introduce synchronization issues as I believe that was the point of this feature.