Admittedly I have a low subscription to Hulu but all the ones greyed out on mine says "Not available with your subscription in Red."
Yes, that is the bug/issue (assuming you're viewing that message in AS). If you were to browse your available content via web browser or app, you'd have access to [at least some of] those movies/shows. Certainly, some really aren't available with your subscription but, for whatever reason, a lot of them appear grayed out but should be available. The 'continue watching' workaround mentioned above seems to work though.