A lot of autonomous feeding behavior seems to be broken, especially for NPC vampires in particular. I made a list for a different bug report, so I'll crosspost it here also in the hopes that it'll be useful:
Played/active vampires will not:
- Autonomously drink plasma packs made from fish or frogs
- Autonomously make plasma drinks or plasma fruit salads, even if they have plasma fruit in their inventory
- Autonomously ask Sims for permission to drink, or autonomously try to drink any any way except for "drink uncontrollably" (likely intended)
NPC vampires will not:
- Drink uncontrollably from Sims
- Drink involuntarily from a Sim (deeply or lightly or drain spirit)
- Ask for permission to drink
- Attack/bite Sims when angry or very angry with them
- Eat plasma fruit that is in their inventory or left out on the lot
- Drink plasma packs that are made from frogs or fish, that is, the packs are created and not bought
- Drink plasma fruit drinks that are left out but not made specifically for them
- Make their own plasma fruit food or drinks
NPC vampires will:
- Autonomously drink plasma packs that are left out and available, or plasma packs that were already in their inventory. As with played vampires, the only plasma packs that work for autonomous NPC feeding are the ones you buy from a PC.
- Order plasma drinks and plasma fruit salad at bars and restaurants. I think NPC vampires will eat plasma fruit salad that's left out or in a fridge that you've made for them, but haven't tested this in a while. They won't make plasma fruit drinks or plasma fruit salad for themselves even if they have a plasma fruit in their inventory.
Club with "drink plasma" as an activity seem to be bugged also:
- Clubs need to be actively meeting with "drink plasma" as an activity
- NPC vampires will first drink every plasma pack they have in their inventory
- Then they'll start queuing up to order plasma drinks at the bar (if meeting place is a bar)
- They will ask for permission to drink from Sims and usually get rejected
- Occasionally they will drink from Sims without permission, but this appears to be a last resort even when they're evil, even though this really should be the first resort in a club specifically made to get vampires to bite people
