How many “Law Enforcement Notice” emails did you receive from Facebook? 1 or multiple?
Did Facebook release the case ID associated with the legal action?
Have you tried a Privacy Act request with the FBI? They may deny it based on “current or prospective law enforcement” but if you were scooped up in a dragnet, they may give you something.
1 (I also emailed them and was told "we can't give you legal advice").
I have the case IDs but my lawyer (Jennifer Granick; she is basically among the best in the world for this) has been unable to get a response from FBI -- they blew her off 5 times.
I did FOIA myself and got "no information since last time you requested" (~10 years ago, which was also basically null)
A Senator's office is involved now. (This is all complicated even more because I currently live in a US Territory where we don't have Congressional representation.)
Did Facebook release the case ID associated with the legal action?
Have you tried a Privacy Act request with the FBI? They may deny it based on “current or prospective law enforcement” but if you were scooped up in a dragnet, they may give you something.