Content on the Roku Channel Will Not Play on firestick

When I try to play "Antiques Roadshow UK" (not the live version—the one with many seasons) on Roku on my firestick I get an error message saying "Service Unavailable / The Roku Channel is temporarily unavailable. Please try again later."

Other non-live shows do play without an error.

The live version of Antiques Roadshow UK will play.