SSRS Optional parameter

Question

I'm not seeing another thread that quite encompasses my scenario: the report I'm modifying has a parameter that I want to make optional, but it is comprised of 3 fields. There is a first name and last name field in which you can start typing, and with the use of a LIKE operator, the actual parameter (Authority) used in the main data pull populates with options that match:

So I've attempted ensuring that the parameters (all 3) have the 'allow blank' and 'allow NULL' checkboxes marked. I've also modified that parameter within the dataset properties to account for NULL:

Lastly, my main query's WHERE clause has the following line: and (data.AuthorityName = @Authority or @Authority is null)

When I declare this variable and set it to NULL, the query does exactly what I want it to, it pulls the data irrespective of what's in this column. But for some reason, I cannot get the report to pull anything. I click View Report and nothing happens. Any ideas?