If I recall,the bone of contention was free Hulu .. now that it has gone the bone has been buried
That was part of the problem and another part was PlayOn lying and stating they were "partners" with Roku. PlayOn went through a period of supporting piracy, or at least appearing to do so, and that caused Roku to look on PlayOn extra critically.
I also think there was a strong cult of personalities on both sides that conflicted and Roku virtually banned any discussion of PlayOn. The reason that PlayOn continued to produce their private channel was that having their channel on the Roku platform was quite profitable.
PlayOn has cleaned up their act and Roku has eased up on the bad feelings and temper tantrums and now Roku and PlayOn are like two children that are finally able to play with the same set of toys at opposite ends of a room.