EB1c interview scheduled interviewed but visa not stamped

My EB1c I-140 was approved. I am an India born UK citizen living in the London. Visa was current and my interview was scheduled for March 26, 2018. They don’t schedule interview if visa is not current. Interview went well, they kept my UK passport, but passport returned without visa. A letter stated that visa retrogressed to Feb 2012.

How long will it take for me to get visa, and if my sponsor is not willing to wait then how may I start working for him?

Hi, we will be going through a similar process. I was wondering if you got your eb1c yet? Or still waiting?