Hi Sam,

FilterZen is designed around most-commonly-required use cases, for example in most cases people want, when "clearing filters", those filters to "go away" and hence data displayed un-filtered. However, what you need can be done right now.

First off, there's this check box setting called "Send filter value even if empty". It is located for every filter type between the "List Lookup Filter Properties" section and the "Advanced Filter Properties" section.

How does it work? When un-checked (the default), then the filter simply sends nothing when the current filter value is empty ("cleared"), so as far as this filter is concerned, all items are being "let through" (shown). When it gets checked however, then the explicit filter condition "Column=[empty]" (figuratively) gets sent. Only items with an empty / no Column value are now included in the consumer Web Part.

This latter option often solves your requirement since often all item Columns are populated. If this is not the case for you, there's another way to make what you need work: expand the "Advanced Filter Properties" section for your List Lookup Filter and scroll down a bit until you find the setting labelled If empty, always fall back to this filter value. Specify a value that is guaranteed to never be a real, existing List Column value in your context, for example usdgfjasghdajhsgfga or oahvshdkef.

This will result in no items being shown whenever the filter value is empty. Ignore the aforementioned check-box option when trying this route.