This is an ongoing issue with some Hulu users. It is unclear why this problem occurs, but there is a workaround that will help you enjoy your Hulu time unbothered by this frustrating problem. Namely, this issue occurs when you try re-watching a series that you’ve previously seen. So, go to the series that causes this issue and open its sub-menu. Navigate to manage series (represented by a cogwheel icon) and proceed to erase the series’ entire watch history. This should help you get rid of the problem.