Thanks for reaching out here in the Community!
Could you tell us how are you powering your Roku Express 4K? Is it connected to the USB port of the TV or to a wall outlet? In some cases, the USB power provided by the TV is not sufficient to power the device. Even though your Roku device may appear to be working, running with insufficient power can lead to instability, crashing, and other unpredictable behavior.
Using the included power cord and power adapter, we suggest plugging your Roku into a working power outlet in the wall. Powering it through a power outlet in the wall has the additional advantage that your Roku player will not need to power up every time you turn on your TV. This means your Roku player will be up and running faster than it would be connected to a TV.
Let us know how it goes.
All the best,
Roku Forum Moderator