Call from consulate for re-interview 5 months after visa stamping.

[Keroque Ke]

Hi, I've attended h1b visa interview in January this year along with my spouse, and was approved visa. The interview was short not many questions. I've not yet travelled to us I am still in India. I am planning to travel next month.

But, Five months after the stamping, today, I've received a mail from Chennai consulate asking me to reappear at the consulate to meet with a consular officer, and that my visa was invalid to travel to USA. I've not received any rfe or 221g during the h1b process or visa interview. Even my employer hasn't received any notice regarding this. This seems highly unusual. Any help how to proceed or why this may have caused ?

Both my case status and visa status remain unchanged on the respective websites showing approved and issued as of today.

Thanks

[Keroque Ke]

Has any one ever came across a case like this ?
I've mailed the consulate, haven't got a reply yet. tried calling consulate and call center but no help.

Any help appreciated. Thank-you