Question regarding Game Mechanics (Thaurissan + Summoning Portal)

Hi, I have a question regarding the interaction between Emperor Thaurissan and Summoning Portal. 

Gamepedia states: "Emperor Thaurissan's effect has triggered while holding a 3-Cost minion. Summoning Portal reduces the minion to 1 Mana and Thaurissan's enchantment is applied afterwards, making it cost 0 Mana."

However, I just tested this. I played an Emperor Thaurissan with a 3-Cost minion in hand and played Summoning Portal the turn after. Unlike stated by Gamepedia, the Mana cost was still 1 instead of 0. Did Blizzard patch this? Or what is happening here?

I've actually posted about this before recently. Yes Blizzard did do a stealth hotfix that wasn't announced during any patch notes. For years Emperor would reduce the cost of minions in the hand and if you played Summoning Portal later on a 3 mana minion (reduced to 2 mana in your hand) would then go from 2 mana to 0 mana. The cards always interacted like this, but in the last few weeks they hotfixed it without any news so that now that same discounted minion will only go down to 1 mana in your hand now.

Thanks for the quick reply/confirmation!

Honestly, since they completely reworked the game mechanics I have no idea what is going on in these more complex situations.

I'm not entirely sure, but I think if you play the Summoning Portal beforehand, the card can be then reduced by Emperor Thaurissan and played for zero mana.