It sounds like they are not willing to even provide an EVL? The only recourse to prove you work there would then be the paystubs, although it puts you in a difficult situation where they have apparently decided to stop you GC process in the middle. They might have done this because of lawyer costs or simply because of political/shift in policy reasons.
Whatever they are, you would be well advised to:
1. File SOMETHING for the RFE. Advice of a different lawyer (certainly an experienced immigration lawyer) would be very useful here, will you get denied based on not satisfying the RFE verbatum?
2. Find a new lawyer and a new company, if you can.
I do get the feeling there might be more here than meets the eye, though... Why would they deny you a EVL when you are employed? Your case might have some additional circumstances.