Originally Posted by
sluneckov
I had similar problem flying LA coded IB operated and after multiple attemps with IB call centre and twitter team I gave up as no one was able to help me and just kept repeating to call LA

bunch of amateurs
Well they do at least assign you a seat I believe once you have ticketed the itinerary as I was assigned 5A on a GRU-MAD leg which I changed to 6A calling IB. May be a matter of having an agent that is willing to do it for you. You can get IB record locator from LA since they sold you the ticket.
Edit replying to OP 😄