The place where took FP doesn't belong to INS.
1. Did the guy at the front door desk ask this question: You have a appointment today?
2. Does the guy at the front door desk wear any kind of uniform which looks like security, or which is different then other clerk inside the office?
3. When you take FP after the long line, when the clerk brings you inside, did you see that clerk cross out your name in the paper?
4. You said within several hours, my FP will be in INS database, why haven't my status's description on INS website changed so far?
If you were him, would you suggest him just go back to china disregard of FP notice? Even if he wanna re-schudle the FP, you need to sign the FP notice. Who could sign it if he would in china?
Suggestion only, don't prefer the risk