Originally Posted by Rukes

Just some more input:

Flying JAL from Jakarta to NRT to LAX, all on AA (codeshare/metal), OWE.

Usually in past years, I was able to get the PNR for the JAL flight, and check in 72 hours before, assign my seat, all that. This year, nope. Even at 24 hours, checking in on the JAL website says "Sorry, it's a codeshare, can't assign seats".

What did work perfectly fine is going to my itin on the AA website, check in there, and it brings me to a codeshare JAL checkin website where I can fully check in and assign my seat. I'm assuming because it's 24 hours, but I wish I checked to see if 72 was allowed. Still got a great seat.

So tl;dr for people that come across this thread for seat selection problems:
Now you have to check in through the AA website to be brought to the special JAL checkin page. If you use the JAL PNR and check in with JA directly, it will not work.