So, we have not received a letter at all. There was never a document uploaded to their account. However, upon inquiring, USCIS responded by email saying, they would now reschedule the interview.
I honestly believe the status should probably be "ready to be scheduled" but for some reason, whoever worked on it, clicked on the wrong button. I am still concerned about the average processing time of said field center being 14.5 month but we are at 22 months waiting time now with no end at sight.
I have just printed out the inquiry form for our congressmen to initiate their support. I'll update when and if things start moving along again.