Hello @danhenthorne -
Sorry you're having this experience. After investigating your specific case, we've confirmed that this is a crash issue that is being worked on with a resolution right now. This will be rolled out in our next Roku Stream release currently targeting a mid June date.
Sorry for the delay,
I don't know if you ever rolled the fix out, but it the app still crashes repeatedly on my Roku Ultra. It has since March. It's hit or miss if it will actually ever work. I tried to use it today and its crashed 5 times without ever actually getting to the guide screen. I have several X1 boxes in my house and only use the one roku uttra. I have in the past deleted the app powered down the Roku for several min and reloaded it with the same thing happening.