The following search returns absolutely nothing:
This probably isn't proper behavior.
While I don't like the 'standard' behavior, searching for answers that aren't closed returns a list of questions that are not closed:
Ideally, anything involving an answer would take the 'closed' status from the parent question, rather than having a 'flag priority' which returns unexpected results (especially returning no results at all, which is the worst possible behavior if there is no indication of what got broken).
For reasons unknown, the advanced search API returns things totally differently.