I've noticed that sometimes YouTube doesn't show ads on my videos, even though they are monetized. Just yesterday I had a video that got 100k views, but on my adsense it showed no ordinary activity. The video was monetized but I tested it in all browsers and sessions but no ads were showing on the video, as was also seen in my Adsense account. How is this possible? My account is partner verified and has over 10 million views.