Ready to schedule interview since May 3, and today got an email from my congressman (I reached out in Jan):
A review indicates your constituent's application has been identified as a potential interview waiver application and is currently undergoing normal processing at the NBC prior to field office review. As an interview may not be required, your constituent's application may be sent to a field office, other than your local office, for final adjudication. Once further action is taken, your constituent will receive notice at the address of record
Not sure why I qualify for the waiver, but I guess that explains why interview has not been scheduled. I did not submit 693 with my application so I expect to see an RFE sometime I guess...