Hi g_sk_99,
Yes, i did travel recently on AP and i have changed job on EAD and have not invoked AC 21. I did not have any issues at immigration.
FYI - probably your Visa might have expired and if you do not have a direct flight and flying via London then you need transit visa....
I am not a lawyer, it would be better if you consult your lawyer since everyones case might be different.