Hi Andy,
I have the same problem on my 65UH8507.
I've called the service center in my country, Romania.
So , follow these steps:
1. Uninstall the apps you do not use
2. Uninstall the app you use frequently. Mine was Netflix.
3.Turn off and unplug the TV set and wait for 5-10 minutes.
4. Plug the TV set. Turn on
5. Reinstall the app you use frequently.
It worked for me. I hope this will works for you either.
