thanks for the bug report! We need report like yours to find the remaining problems. 3 remarks
1) This sub-forum (AI bugs) is supposed to be for problems with the game's bots (Lord Rattington,...). This report would have been better in the "Card Bugs" sub-forum. Not a problem, just a small remark.
2) I found your games with Sille71, including the one with Necromancer (13554187). For some strange reason, they all seem to end very far away from a real game end, like Prinvces gones or 3 piles empty. Did one of you resign on those games? Otherwise is would be a problem if games are only 'half recorded'.
3) Due to 2), the game did not contain a situation where the Necromancer was played as you described (also, because you undid it). I tested the situation in another game, and it worked without a problem: The 1 and only card was drawn, then the game continued without revealing anything (as there wasn't anything to reveal).
Do you remember maybe another circumstantce that could explain why the effect didn't work in your game?