Originally Posted by
Deckter
It's not random:
"Please bear in that mind check-in for flights to/from Cuba, El Salvador, United States, United Kingdom, Guatemala, Mexico, Puerto Rico and China only opens 24 hours before the departure of your flight."
https://www.iberia.com/us/checkin-information/
So it probably means that IB is blocking the possibility of online check-in for these tickets.
Not good - I guess time will tell