Min and Max columns on Assignment Effective Dates are blank in OTBI analysis

Summary:

'Latest Assignment Start Date', 'Earliest Assignment End Date' columns showed data while building the report. After adding more columns and filter condition these two columns are blank.

Content (required):

The attached report joins multiple Subject Areas - Assignment Events (History), Person Real Time, Payroll Run Results and Absence Real Time.

'Latest Assignment Start Date', 'Earliest Assignment End Date' columns showed data while building the report. After adding more columns and a filter condition based on Paid Date

these two columns are blank.

I noticed, after removing Eligibility, Eligibility Notes columns and removing a filter for Paid Date, it does display results in those columns. But those columns and the filter are needed in this report.