I don't know the answer, but if it's one PNR, it could be that the computer simply says it's the same as if I were going to Europe via ORD from MCI on the same day. If that's the case, it actually may not allow you, regardless of the perceived logic. I am also not sure that calling will get you the correct answer. I definitely am not the person to ask but I am so curious about this. One thing you may have in your favor is that when I have a long layover and check in 24h in advance for my first flight, it does not allow me to check in for the next flight because it's not 24h from that one. Still, you don't need an airport surprise on what appears to be a major journey.

Can you get the passport? Can you see if the ticket can be broken into two? Please update us.