Cooking always fails since upgrading to 4.12. Log is attached with all the info. I’ve followed suggestions from this thread about Preview 5 but no resolution has been posted. This is a pretty serious bug to have made it from pre-release to full release.
This was caused by our custom OnlineSubsystem setup as a Plugin. Not sure what change happened that would cause this to break, but we’ve made the switch and hopefully that will be that.