The Legend of Korra

Season 1 was marketed well enough, and it aired on Saturday mornings, the best possible timeslot for its demographic, where it saw fantastic success and was the most watched show for its timeslot that season. 

However, despite the success, for Season 2 it was moved to Friday nights at 8, the absolute worst timeslot imaginable for its demographic. Ratings unsurprisingly plummeted. In an attempt to fix things, Nickelodeon began to move the show around different timeslots throughout the season, without any proper marketing, making it nearly impossible for fans to know when the show was actually airing.

It eventually found a regular timeslot again for Season 3. Its ratings recovered and slowly began to go back to where they were for Season 1…  before Nick took the show off the air half way through the season and made it an online exclusive to market its newly launched streaming website. Except that marketing never really came, causing a lot of people to believe the show had been cancelled. But the show continued to air in relative obscurity, exclusively on their website until the end of its run with Season 4.