I have 2 Roku Streaming + sticks and both work perfectly on my Toshiba TV. On my RCA Smart TV the Roku screen will load fine. I can get to all my channels but if I choose a newer show/movie on Netflix (first happened when trying to watch Extraction) the Roku will suddenly start to cut out and a "Source not connected" will show-up, then it will load again followed by being cut out once again. If I play Disney Plus some movies do the same thing. I tried to watch Avatar and no sound would play but if I backed out and played another movie the audio was suddenly fine.
I have disconnected my Roku, changed the power plugs. Rebooted, checked for updates. Checked internet connection which always is connected and has excellent strength. I swapped my Roku sticks and which ever one is plugged into the RCA tv will have problems but work perfect in my other TV. I have used the stick in my RCA tv for over 4 months with no issues so not sure why it suddenly is having these issues.
Mine does same thing when trying to watch some things on Disney+