For example, the Select Expert formula is:

{GfCnMem_1Cur_Program} = "xyz"

If the record does not have a value for the Current Membership Program, the value is null, then the record is removed from the report. We need to change the Select Expert formula to allow null values:

(if not(isNull({GfCnMem_1Cur_Program})) then {GfCnMem_1Cur_Program} = "xyz")