Nothing's changed. The point of a bounty is to get attention not an answer. This doesn't necessarily guarantee an answer. Our policies on that haven't changed. If you have the rep, and want the answer you'll just have to keep posting (bigger) bounties until you get it, and see if the extra attention will help.
A bounty is best used as a last ditch effort to get an answer, and if its a properly interesting/difficult question, it may not be answerable anyway.
What gets you an answer, aside from having the right person seeing it is, well posting the best possible question you can - just enough code for someone to work out what's wrong, any relevant errors (don't just dump your logs) and so on.