Can interview waiver appointment be revoked by consulate?

I am applying for a J1 visa, and I qualify for an interview waiver. The international office of the university told me that they had applicants who initially qualified for a dropbox appointment. However, they were later revoked by the consulate. Has anyone heard this case in India? Or is this even true?

IW aka dropbox is at discretion of the consular officer. In most cases J1 are called for interview due to the nature of visa.