LIN filler here, still no update about biometrics letter, sent them request about case out of the timeline or (whatever its called)))) got email after 1 month saying i should be patient :))))
also traveled with expired GC and ext letter, Turkish airlines rep was super knowledgeable on the way back through IST, had no issues.
Entered with Global entry - smooth like a butter, it didn't give me paper and sent me to the officer, but officer was super sweet and stamped and let me even ahead other people because i had expired GC and ext letter + Global Entry :)) tip: give all the documents together to the officers, i saw they really like when people are prepared and dont waste their time.
Good luck to us all