I noticed the same thing. XL1439 is unbookable. My husband and I are booked for Dec 23, and our booking looks normal on LATAM's web site. However, we now have a cousin who wants to go. There's no indication the flight is cancelled but we can't book him a ticket.

My husband flew JetBlue's JFK-GYE service last week and reported it was good. They're blocking middle seats, which is nice, but JetBlue offers no business class yet to GYE. LATAM's is usually available for only a small premium over economy, so we usually book that.