I have a Philips ATV on Oreo. Tested Aerial Dream as a screensaver and it works good when using the ATV. It activates after no use in X minutes. But when using other sources, ie my computer through HDMI, it activates even when the computer is in use or a movie playing. Anybody know why? A bug?
So this happened to me when I messed around with the timeout settings using non standard software and was driving me crazy. Luckily I found out the issue in the end, but if you cannot find it , you can fix it by hard resetting your tv to factory settings.