I have a Sharp Roku TV, it's about 3 years old now. All Roku apps functional normally except my YouTube TV app. About 3 weeks ago it simply stopped loading the app. The TV hangs for about 60 seconds totally frozen then reboots itself. No change in functionality. They same app loads just fine on a Roku premiere I have on another TV.
The usual suggestion is to delete the app; then go to home>settings>system>power to do a "restart." (If the "fast start" option is enabled, I would disable that. It keeps things in memory, never reloading fresh copies. Things go bad, and stay bad.). Then install the app.
If that doesn't work, then people are told to contact the app's support.
Before trying that, I would try the so-called "clear the cache:"
Hit HOME 5 times. UP once. REWIND twice. FAST FORWARD twice. (Clears cache & tv reboots itself. Be patient. It takes 2-3 minutes for the tv to go black, and come back on)
That's known to fix odd problems. It wouldn't hurt to try it. I'd try it first.
"People are often amazed at how much we’ve done with the number of engineers we’ve got." (Roku CEO Anthony Wood, Austin Statesman, Oct 4, 2019). "Amazed" is one way of putting it.
After restarting my Roku TV, the YouTube app started working just fine........If that does not work, power off the TV and unplug the power wait 30 seconds and power back on. Hope this helps someone.....