Thanks for the note. Are other channels working correctly on your TV? Have you contacted YouTube TV support yet to report the issue and request additional assistance?
I'd recommend removing the channel from the Roku home screen, restarting your TV from Settings>System>Power>System restart, then adding the channel back once more. You might also try disconnecting the power to both your wireless router/modem for a couple minutes, then plug them back in to fully reboot them. Go back to Settings>Network>Wireless>Set up connection and enter your network details again. Then try to stream once more.
If those steps aren't clearing up the issue, and other channels continue to work normally, you'll want to follow up with YouTube support to report the issue in their channel and request additional assistance. You can reach YouTube TV support here: https://support.google.com/youtubetv/?hl=en#topic=7071745