Still waiting for approval status for premium: Applied in April !!

Employer applied under Cap Exempt in Mid-April and then converted the petition to Premium 1st week of May with one RFE, due to lost documentation by USCIS. Still have no status update !!

Lawyer is saying that it maybe due to my Nationality, as it is one of THOSE ones. Possible reason?

May be, but no one will openly admit it.
All the best. In any case they have to give a decision 15 days after the RFE has been submitted.