We encountered an error preparing your project. Error: errors.com.epicgames.content-service.cook-failure, An error occurred while communicating with the game servers (Content (re)cook error errors.com.epicgames.cookplugin.cookfailure.
It just stopped happening after I walked away from it for a few days and re-visited. No idea why or what - the response rates here from Staff are generally quite poor so you never get a proper understanding of whether stuff is broken or you’re not using it right.