I recently ran across what to me is clearly an off-topic question on SO:
This question is clearly asking that someone recommend or locate a library or tool, which is a shopping-list or recommendation question. However, it can't be closed, as it has an open bounty.
The typical process for these types of situations is to flag the question with an "other" flag, and explain that it's off-topic but protected from normal closure by the bounty. This has been previously discussed here, for instance in this question - it happens to be opinion-based, but the concept is the same; it's an off-topic question that was unable to be closed as usual because of the bounty. (As can be seen in that question's answer, the flag works, and I posted an answer there that mentions that as well.)
I flagged the question, with the specific reason I mention, and the flag was declined:
As the question can't be closed by the usual process because of the bounty, and is clearly off topic according to the guidelines here (there's even a standard site-specific off-topic close reason for these types of questions), there's clearly moderator intervention required.
Are off-topic questions now immune to closure because a bounty is added?