Welcome to the Roku Community and thanks for posting regarding the Hulu channel.
For clarification, the Roku platform is merely a means to stream content through channels that are provided and maintained by the channel provider, in this instance Hulu. For more information about that channel's authentication and functionality, you'll want to contact the channel provider support directly to inquire further. Many channels on Roku are developed and maintained by the channel provider themselves.
Have you already tried removing the channel from the Roku home screen by navigating to the channel tile, pressing the * key on your remote and choosing 'Remove channel'. Then restart your device from Settings>System>System restart. Once your player starts up again, add the channel back once more, specifically in that order.
Does this clear up the issue you are seeing? Please keep us posted what you find out and we will be more than happy to continue assisting you.
Roku Community Moderator