I just received cancellation emails from both AA and B6 for two trips later this year, booked thru AA for travel on B6.

on aa.com, the trips show "changed" and "our system is having trouble". but the trip is still there.

on the jetblue app, the trips are still there, and i can change seats, which i couldn't do last week on these trips..

EDIT: now the AA site shows the B6 flight number instead of AA9xxx. Guessing they were just removing the codeshare flight numbers and did it very very badly.