The On-demand comparison filter has no pre-selected metadata types. So applying it has the same effect as the None (0) filter.
Our On-demand comparison filter is created for when you want to load up a comparison quickly without pre-selecting a filter.
Once the comparison page loads, you can then add the metadata types you want to retrieve to your filter, or you can select your preferred filter (whether it's a custom filter you created or one of our pre-defined ones).
More details about using the new comparison window can be found here.