Shaper's Sanctuary doesn't seem to trigger

Machine

Shaper's Sanctuary is a very mediocre card. I thought the best way to use it is in PvE where you'll know when your creatures will be targeted. So I thought to give it a try in A World Reborn node 2.2. My creatures were targeted by multiple kill spells during that match (and of course died), but Shaper's Sanctuary didn't trigger and didn't lose a shield count. My hand was NOT full at that time. A very mediocre card becomes a useless one. Can you please investigate?