How do I get my report to return the unique values that should be displaying for each line item?

Your field has displayed on multiple levels of the Field List tree, and you  have selected from a level that does not correspond to the line item  section of the report. 
Drill to the next level of the field list tree so  that the field dragged into the report has the correct relationship set  up. By selecting from deeper in the tree, the SQL behind the report can  "see" the individual values for 
each line item and returns them,  instead retrieving the first value and repeating that value on each  line.