Microsoft Offer - TN visa problem

I went through MS interviews, had offer, negotiated and signed offer letters, successfully cleared the background check and ran into issues at the last step of TN-1 visa. They simply said that MS immigration team sees risk in securing an appropriate visa for my work authorization. No other reason given. This was a big surprise since I had TN-1 visa multiple times in the past and had worked at MS as a vendor. Also, I've always known MS immigration team to solve very complex visa issues. An external independent attorney, whom I consulted with, assured me that I had all the required qualifications and the job also matched TN-1 visa requirements. I've been trying to reach the recruiter and the responses are becoming slower and slower. On my last phone call I requested the recruiter to connect me with the IMM team to rectify any possible miscommunication or documentation gap. I'm still hoping and waiting to hear from IMM team. Did anyone experience a similar situation? Any suggestion or thoughts would be appreciated.