A recent notification on www.ustraveldocs.com/in, the official U.S. Visa information website for U.S. Missions in India has recently updated that the U.S. Embassy and Consulates in India are experiencing technical difficulties and this is causing delay in issuance of visa for some cases.
Further, this update also specifically advises student and exchange visitor (F/M/J) applicants to specifically carry proof for payment of SEVIS fees.
This update is available here.