I've used this trick on a Roku 3 and a Roku 4 and it worked on both. If there's no "reset / clear cache" option for you on the secret settings screen, it might

I've used this trick on a Roku 3 and a Roku 4 and it worked on both. If there's no "reset / clear cache" option for you on the secret settings screen, it might take a little while for any downloaded ads to expire.