I'm having the exact same problem. I've tried all of the suggestions in the various threads and nothing has worked. Hopefully someone can tell us what's going on.
Just to reiterate, all of the other Roku apps are working fine.
I got a message that there is an outage in my area, but it didn't specify streaming service. I tried the streaming app on my Android phone and got the same lack of performance, so I'm going to work on the premise that it's a streaming only issue which is why I still have WiFi access on my phone an laptop for Internet, but not TV.
On the phone I get "Playback Error::10600", but on my TVs connected to Roku, I get a blank screen.
I guess I can hang up my phone and wait to see if they get it back up around 5:00PM which is what they claim.