Well it appears this was nothing to do with US departure or arrival. My flight in two days is JED-LHR and I am getting exactly the same issue again. My colleague can check in but I still get the redf bar at the top of the screen that says "Sorry, an error occurred while processing your request. Please try again later or contact our customer care."

And this is despite getting an email asking me to check in.

Only customer care I can get is a useless bot that may as well be a brick wall.