Having trouble selecting better seats during check in. I was auto assigned some pretty awful seats but plenty of seats closer to the front that should be free to choose.

After I hit submit to lock in my better seats, I get this error. I booked it through BA so it has a BA flight number as a codeshare. I have tried using BA site, Iberia site, Iberia spanish site, mobile apps for BA and IB, and 3 different browsers.
I always get this error.