CacheDuration is not respected

[amilici]

The image is never downloaded on (iOS, not sure about Android) again no matter what the cache duration is.

If I have this in the xaml:

<ffimageloading:CachedImage
          Source="{Binding ImageUrl}"
          DownloadStartedCommand="{Binding DownloadStartedCommand}"
          CacheDuration="00:00:01"
          HorizontalOptions="FillAndExpand"
          CacheType="All"
          VerticalOptions="FillAndExpand"
          Aspect="AspectFill">
 </ffimageloading:CachedImage>

The image is never downloaded again even though the CacheDuration is 1 second. If I set the CacheType to None it is downloaded every time as expected. Am I doing something wrong?