This happens on two Roku devices which I use to watch Xfinity stream TV. It is cleared by hitting the power button to turn the TV off and then turning it back on again.
Roku device 1: Model = 3941X - Roku Express 4k+, Ser# = X01600AUL89N, Dev id = S07P21AUL89N
Roku device 2: Model 4800X - Roku Ultra, Ser# = X01000W4R33W, Dev id = 502A2194R33W
In both cases OS Version = 11.5.0 build 4235-cr
Not sure if it happens on other channels, but it happens on Xfinity Stream Ver 6.9 build 0
Tracker issue ID 9N-467-372