Bookmark this guide. Try Fix #1 (Clock Sync) and Fix #2 (Sign out/in) first—they solve 80% of cases. If those fail, the reinstall (Fix #4) is your silver bullet.
Based on archived release notes for :
: Supports resolutions up to 8K and is optimized for TV remote controls. No Google Services Required smart youtube tv 617 740
: Capable of streaming in 4K and up to 8K resolution if the hardware supports it. Bookmark this guide
It unlocked high-resolution streaming even on boxes where the official app capped out at 1080p. Ad-Free Experience: smart youtube tv 617 740