Cast always fails for inheritance

The build-in types work. But the whole thing all together is strange at the very least. Also there is a case where you cast parent–>actor–>child where the engine gives me a warning about parent already being an actor and thus there should be no need to cast it to one. But I HAVE to cast it to the build-in type in order to cast it to a child-blueprint. Bug or me?

Casting from Actor → child works.

Casting Parent → Child always fails.

But casting Parent → Actor → Child only warns me that Parent is already an actor and that I do not need to cast it to Actor. Even though it should be the same as the above line. But it is not???