What happens if you are hidden and you cast with Subtle Spell a spell that involves a saving throw?

@JeremyECrawford Unseen Attackers (PH, 194–5): works with attack rolls if you are hidden.
But what happens, if you are an hidden Sorcerer with Subtle Spell, and you cast a spell that involves a saving throw? Are you still hidden? Can you cast an hidden Fireball or Charm Person?

— Draconis (@DerynDraconis) January 12, 2018

If hidden, you stop being hidden if you make appreciable noise (including the verbal component of a spell), you make an attack, or you're spotted. If you cast a spell that involves none of those stoppers, you're still hidden. #DnD https://t.co/epMrRT2rL8

— Jeremy Crawford (@JeremyECrawford) January 12, 2018