I assume you've been working on several different bugs in the co-op campaign? I'm on the final mission and was hit with the "Halley Exception on Entity" message, preventing any progress. I posted about it on Discord a couple Sundays ago but have been ignored thus far. Like I said there, I'm patient, but would appreciate knowing at least that a fix might be coming.
Hi there, yes fixes are being worked on at the moment, we've been trying to recreate these bugs for them to be resolved, but we'll share as soon as we have an update. Sorry you've run into issues! Were you both playing on Steam, or different platforms?