It sounds like a AVM glitch to me !!!
My case was similar with your case. I replied back to INS about the RFE. AVM was updated about it and two months later AVM was changed
to "sent RFE" so I thought I was getting the second RFE. But i had no
clue what it was about because my company is one of the largest company in US and the frist RFE was about w2, emp letter and paystubs.
And then it tuns out that it was AVM glitch.
So if you can, do the fax inquiry and ask your lawyer to follow up.
Good luck !!!