Well, this is strange... It worked correctly now. I don't understand what happened, I used the same deck and the same method as before - casting a bunch of moxes, hurkyll's recall, recast them, timetwister, another hurkyll's, repeat, until >20 storm count. Only difference is the game version, because that did take place some weeks ago, but I doubt the way the game handles milling changed in the meantime. I'm really sorry for wasting you guy's time with this, seriously sorry! Just can't understand what happened, I saw it happen, like, I have no reason to lie... Maybe I was seriously drunk or something...
Tl;dr: Mistaken bug report, forget it. I'm sorry!
Edit: only thing I can think of is if maybe the AI had something in the deck that would reset the library, something like
Gaea's Blessing, and somehow I didn't notice it.
Blessing isn't available, maybe there's something similar to it. Maybe I was drunk?
Edit2: Ok, I figured out what happened. I was testing that deck when I was trying to come up with something that could face the illegal top Vintage decks from Firemind - I gave up on it when I figured the AI wasn't capable of playing this strategy. I playtested it against what was the top Vintage deck there at the time, a 4x
Tinker 4x
Time Walk 4x
Ancestral Recall etc. deck. That deck... had a couple
Blightsteel Colossus!!
God, I'm stupid.