There's a difference between an actual vampire break-in event and a visitor at the door (who just happens to be a vampire).
The game will have random door knockers, usually throughout the daytime these will be random sims that give you a chance to make a new friend or meet a stranger. The game still has these in the evening too, and some of these might be vampires, because they're allowed out during the night. They are still just rando door knockers and aren't there to break in.
A true vampire break-in event will start with them creeping on to the lot, and they won't bother to knock, they just come in, mesmerise your sim and then drink plasma. These can be easily aborted - a vampire will only break in if all sims in your house are asleep by a certain time when the event begins. If any sims are awake, or if you have a pet or a roommate NPC that are awake, the vampire will turn around and leave. You might not even realise an event even happened if the vampire spawned in at a spawn point far away from the lot, detected your sims were awake and then turned around and left without you even seeing them.
That's why I see vampire break-ins easier in San Myshuno apartments - because the spawn point is the elevator in the lobby, you have a greater chance of seeing them arrive and then leave (or proceed and break in).
I don't think there's a bug here if all the stuff above is happening - that seems to be the intended gameplay to me. For a break-in to be successful and actually happen, you need the perfect conditions (all sims in the house asleep at the right time). Ignore random door knockers - that's a totally separate thing.