I've never encountered this before today. It has always worked correctly, but I lost a match and rank today as a result of omniscience not interacting correctly with x spells. I had 2 x spells in hand with 13 available mana (lands + Ugin activation). The two spells were "Portent of Calamity" and "Doppelgang". I went to cast Doppelgang for 3 to finish milling my opponent out using Scrabbling Skullcrab's ability, but it would not let me choose a number other than zero. I tried multiple times, changes game settings, and even restarted the client. Nothing worked. I then clicked on Portent of Calamity and the game chose zero and put it directly into the graveyard. I had to pass the turn due to time running out by trying to all of those fixes and then lost on the opponents next turn. I would appreciate some level of compensation and for the bug to be fixed. Thanks for your time.