My virtual onsite interviews were scheduled to happen in two days. Recruiter emailed me today saying Immigration team asked not move forward and when I asked for details, recruiter said he cannot reveal anything more.
Any idea what must have happened behind the scenes?

I still have around a year in my work visa so visa shouldn't be the problem.

I felt this was unfair of facebook (especially when they refused to give any details) as I had spent months prepping for this interview.