Been having the same problem for several months. At the latest woftware release for the Roku Express 4K+. Can only fix by rebooting the unit.
@RokuDanny-R:
This also happens on my device, and occurs every few days. It happens on a range of different channels, not a single channel.
Model: 3820X - Streaming Stick 4K
Serial #: X017001WWRD2
Software version: 11.5.0 - Build 4312-CU
Device ID: S08Y425WWRD2
I don't have a tracker id, as I did not preserve that from the last time it happened (about 4 days ago), but will do so the next time. I am not aware of any specific steps that cause this to happen, but will pay attention next time if there's anything specific (aside from being in the middle of watching) that seems to trigger this.
Assuming this is occurring on Roku DEVICES rather than Roku TVs...
Has anybody with this problem tried disabling the Auto-adjust display refresh rate setting? If your Roku has this setting, it is found here:
Settings > System > Select Advanced system settings > Advanced display settings