Considering how the NBC has gone ahead and scheduled everyone else (reporting in this forum) for bio (since the USCIS offices re-opened for in person service), and they’re yet to schedule you for your bio to start with, it is possible the NBC is still under the impression your AOS is family based. If you like, you can send me a copy of your submitted I-458 via email for me to review to see if there’s anything on it that could be causing this confusion - (sm1smm555 at gmail).
Now, if it is any consolation to you, the letter you got is what I refer to as one of the standard responses USCIS sends out when they’re not ready to make a commitment for one reason or the other. Clue to that? The letter states your case is still undergoing some review at the NBC. Meanwhile, the FO previously sent you a RFI, right? If the case file was still at the NBC, the FO wouldn’t have sent out the RFI back then when they did. Also, the service request you raised wouldn’t have gone to the FO because the phone rep wouldn’t have known which FO has jurisdiction over your case file if it was still at the NBC.
So you can either forward a copy of your I-485 to me for review as a first step, or if you’re certain everything is in order from your end, keep calling the 1800 number and continue to plead for an INFOPASS appointment to enable you visit your FO and plead your case in person.