Tip: Remove white space from cell and replace with null or a value.
If you have cells with white space (no characters but not NULL either) see attached pic for example. You can use this on your column element for an infolink. Start with NULLIF(%1,''), this will remove white space. Then if you want to change your now NULL cell to something else use this. ISNULL(NULLIF(%1,''), 'BlaBla') this will then change the NULL to BlaBla.
The main thing this will do is clean up your filters. See the after pic also.