If true, this is just about the dumbest bug I’ve ever seen. Two prompts, identical effects (both poison the drink), one is Consumed Poison and one isn’t. I’ll test it as soon as I can.
Can you test poisoning from behind the bar to see if it stops registering for you?
EDIT: Based on this and the Landslide woman’s drink that doesn’t count either, I suspect that Consumed Poison only registers if the prompt to poison the drink itself tells the game that it’s Consumed Poison. This appears to need to be set for each specific poisoned item, which might be how IOI misses a few here and there. They set the front prompt for Novikov correctly but forgot the back prompt, forgot the lady’s glass in Landslide, etc., but correctly set things like Dalia’s two wine glasses so both work right.
Needles probably work consistently because the game always just sends a “this is Injected Poison” thing to the score system whenever you use the prompt to kill somebody with one. The score system only counts “Poison” if it’s either Consumed or Injected, so all other Poison Kills count as nothing and don’t satisfy the generic “Poison” condition. That’s my guess.