They are not bugged so much as overloaded (though not being able to handle the load is itself a bug). Most of them have spawn rates for the NPCs you need. When too many folks are hanging around, things seem to get off, and either they don't spawn often enough or they spawn and are instawhacked so quickly people don't get the required result.

Each time I've encountered this problem (in beta and since launch), I've gone off to do something else, then come back later when fewer people were around. (Being on the west coast means that if I wait until my end of day, most of the rest of the country is off to bed already.)

I'm not excusing the fact that this occurs - just explaining my way of dealing with it.

They know what the issue is, they just haven't been able to fully resolve it. If it happens to you, move out of the area, relog or do something else for a bit, come back and hopefully have a new instance.