Have a Roku Streaming 4K. on startup get all visual menus, sound, and guides in multiple apps (YouTubeTV, Roku, Disney+, ESPN. When select content, sound works, but no picture. Can still pull up all visual menus, so definitely not a cable or connector issue.
Restart typically solves, but occasionally will still have image drop out a few minutes later. Menus still pop up. Sounds like a software glitch to me.