How to get getComponentsByTag to work on child components

Hi everyone,
I have an Actor with a root component “body” and a scene component “engine” as a child of the root component. When I use getComponentsByTag on the actor, only the body shows up, the engine does not, despite beeing the right class and having the tag. Is this intended? Do I really have to iterate manually through every child?

currently looks like this:

UTestEngineModule* engine = NewObject<UTestEngineModule>();
	engine->AttachToComponent(vessel->body,FAttachmentTransformRules::KeepRelativeTransform);
	vessel->body->GetChildComponent(0)->ComponentTags.Add("tag");
	TArray<UActorComponent*> results = vessel->GetComponentsByTag(UActorComponent::StaticClass(), "tag");

I manually checked that the hierarchy is right, and that the tag is actually there.

Im doing this inside an automation test, if this has any impact.