Safeguard notable doesn't appear to work

I'm specced into Safeguard (8% ele res, 6% spell block, recover 50 ES on spell block) and Glancing Blows. I have 75% spell block and I see other things proccing from blocking spells, such as Whirling Barrier (20% chance to gain a power charge when you block), but I don't see my ES recover ever. Tested by standing in the floating Whirling Blades environment objects in Overgrown Shrine, perhaps they're not spells.