Regional maps that I have previously completed and viewed in the past do not load. Local maps seem to load fine.
Scratch that, just tried again and local maps aren't going now either. I dont think this is a result of lag, at least not due to online player counts because it doesn't work now with 300 online and it didn't work earlier when the count was only 120 or so.
edit: embarrassing typo, apparently there is an 'o' in counts