Ok so the idea is
One of the item types is cursed (opera glasses, tabloid, etc.) each night. Presumably a different one each night so it isn't as solvable.
For each person who selects that item there's a 1/n% chance they're converted to mafia (so 100% if one chooses, 50% if two, etc. etc.). Presumably only one conversion with the convert chosen from the selectees, rather than independently determined for each selectee.
The person you try to target with your item is NKed instead
Again this is not a concrete theory but its kinda my working theory atp