I'm in the same boat. I'm flying LAX-HKG-SGN rt in February. My SGN-HKG flight has been downgraded to coach. HKG-SGN is still showing as J.
Expedia also showed all flights as Economy but with the correct booking class code J.
Weirdly I also can't access my itinerary anymore on wikipedia since a couple hours ago. Says it doesn't find anything with my email/itinerary number. Hopefully that's just a glitch with Expedia.