I have the exact same problem with my Roku Premiere - HD and 4K UHD Streaming Media Player. Whenever it happens I switch back to my TV, then switch to the Roku again, and it has worked correctly when I switch to it the second time every time thus far. It's a nuisance and I'm concerned that it might not work on the second, third, etc, connection at some point in the future which would render the device worthless. That's why I was searching the Internet for a fix.
I have the exact same issue with my Roku Premier Plus that was purchased a week ago and the Same Sony TV (55 " version). If I remove the power from the back of the ROKU and immediately restore it, the problem is fixed. I currently am using HDMI 3,not sure if it happens on all inputs? I noticed when you hit the input on the TV Remote - the Roku Box and Roku HDMI cable are both listed. Not sure if that has something to do with the occasional mirror images?