I've just noticed recently that once you finish watching the daily ads, there would usually be extra ads that pop-up every 5-10 mins. Although, now when they do show up I click on it, watch it then all of a sudden the ad disappears without getting the coins.

Has anyone else encountered this?

I see the whole ad, but there is no reward. I also have to log out to close the ad.

It works the very odd time, maybe once out of the blue.