A Comparison Type determines how the Draft - Filter does its filtering. 

...

This Comparison Type is unique. All Draft - Filters with a FreeText Comparison Type are gathered into a single filter with an ID of "freetext". 

Due to the inner workings of how such filters work, any search, which has a freetext filter MUST be populated (see UseSolr for a guide on how to populate a search).

FreeTextAutoAsterixing
Equals

Tests whether a Draft - Filter's parameter matches exactly with the data, the filter works on.

...