回複：Help: J-1 waiver receipt

There is one guy who told his story before,you may check with J1 waiver or I612. He said his case processed for 9 months in USCIS, After he called them, he was requested to fill out I612 form and fee.
Two possibilities for your case: 1. the application form should be done by DOS has lost, thus USCIS does have your application number; 2. mistake made by USCIS.
The best way is to call USCIS and ask them.