You won't generally find information like that on a user support board. And, quite honestly, you won't find Roku news releases about Roku Channel content that is not original content.
Roku licenses the content either directly from the content owner, or from a third party who has the license to distribute. Sometimes, one service gets an exclusive on certain content, meaning other services have to drop it. Sometimes, the license expires and another distributor has it. There are several reasons for content to disappear from a streaming service. It happens all the time. One of them just so happened to be something you were watching this time.
You can search on Roku for the content, and if it doesn't show under another service, you can add to your feed. Then, if it appears on a service, you'll get a notification.
DBDukes Roku Community Streaming Expert Note: I am not a Roku employee.
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