That's not been my experience, I'll have to give it another pass
Keep an eye on the lighting conditions. You'll want it to be at least partially obscured to sneak through a vision cone. And a decent stealth score, of course.
I actually tested this out yesterday in the dank crypt. Astarion Stealthed when the skeleton with the scimitar ran RIGHT past him. I had him in leather. Astarion is a boss Stealth person now. I kid you not, the skeleton went within 5 feet of him on Astarion's right. The roll was made and Astarion succeeded. And other scribes put him in their vision cones and he still hid. So Stealth is definitely working.
As for Hugi the Third, nobles are fickle creatures. You never know what kind of things they'll do. Someone has to wear fancy padded armor at some point. Right?
