The sad part of this issue is I can even tell you what it is doing, it's playing the video at 1080p, which is 1/4 of the 4k TV resolution, so it is only showing in 1/4 of the screen. Something with the latest update is causing the Roku not to upscale the video from 1080p to 4k. I don't know if it's only limited to a few apps, my problem is specifically with YoutubeTV, which is my default app when I turn my system on. All I have to do to fix it is go back to the main menu, then start the app again. This is annoying, but it works. I agree the asking what brand and model of TV is annoying and a waste of time. I can't believe they don't know or can't figure out what is wrong when it is obvious, they just need to figure out how to fix it.
I have only had the Roku Express for 1 day and like so many others I too have had the same issue where the image covered just over a 1/4 of the screen. I tried changing the display settings but without success.
I took Katmac13's advice and restarted the Roku Express!
Just unplug the power USB cable, give a few seconds and plug it back in.... guess what it works and back to normal.
Clearly this behaviour isn't normal and could happen again. So Roku Support your input and a firmware update to fix this issue would very much appreciated. There are so many people experiencing the same issue so please fix it.
I’m having the same problem with my Vizio D24f-F1. Factory reset everything but it still does this. The Vizio Smartcast plays full screen but the Roku will not. I got the Roku only for the Spectrum App. The Vizio Smartcast won’t play the spectrum app.