So I think it's definitely what Soulless described, but I made the video anyway 'cause it's interesting. We also don't have any footage of the medals, and we didn't think to check them at the end. Here's the video

Recently played chris' campaign in online coop and somehow skipped the final boss entirely. I couldn't find any info on the bug, so I thought I'd share. Both me and my partner have footage of it, but I wanted to see if it was already known about before I edited our clips together.