I went for my H1B interview on Jan 4th. I work full time for a MNC. The interview was going ok when the VO said that he sees on his screen that I overstayed on my F1 visa. I for a fact knew that I had never overstayed, so I was surprised. He was really polite though and issued me a white 221g to provide documentation that I did not overstay and said he can review it once I send in the docs. I mailed the docs on Jan 7th and got a mail requesting my passport on Jan 8th. My visa status changed to Issued on 8th and I picked up my passport with the visa stamp on 11th.