Q&A answers not publishing
Recently I had a slightly different but similar issue with answers in commons. When a user answers a question it was by default visible to trusted contacts of that user but not visible to group members and there was no way to change that even as an admin.
After spending quite some time, I tried disabling the commons feature "Commons Trusted Contacts" which solved the problem.

So, one thing is clear it is this feature/module which is overriding. If you don't need trusted contacts functionality, you can just disable this. Otherwise, Commons trusted contacts is the right place to look into to solve the actual cause.