I have the exact same problem with Youtube and Youtube TV, I restarted the system and even tried unplugging and rebooting, nothing works. It has been working fine since we installed the Roku device until today
When a channel is misbehaving, the first thing to try is to remove the channel, reboot the Roku, and add the channel back. Do not forget the reboot step, or the removal is not completed.
Dan Roku Stick (3600), Ultra (4640), Ultra (4670), Ultra (4800), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.