When an opponent has protection (The One Ring) or hexproof (Leyline of Sanctity), the scry ability of Palantir of Orthanc doesn't trigger. I think this is potentially due to Palantir's later ability which targets an opponent, but this comes after the scry trigger.
Palantir's Text: "At the beginning of your end step, put an influence counter on Palantír of Orthanc and scry 2. Then target opponent may have you draw a card. If that player doesn’t, you mill X cards, where X is the number of influence counters on Palantír of Orthanc, and that player loses life equal to the total mana value of those cards.
I've run into this issue at least 5 times recently, it's pretty consistent.
Palantir's Text: "At the beginning of your end step, put an influence counter on Palantír of Orthanc and scry 2. Then target opponent may have you draw a card. If that player doesn’t, you mill X cards, where X is the number of influence counters on Palantír of Orthanc, and that player loses life equal to the total mana value of those cards.
I've run into this issue at least 5 times recently, it's pretty consistent.