How many records Microsoft Access reads depends on whether or not the field is indexed. If the field is indexed, Microsoft Access reads only the unique values, not all the values in a field. If the field isn't indexed, Microsoft Access reads all the values in the field. If the number of records it reads is more than the maximum it's allowed to display, which is determined by the setting for Don't Display Lists Where More Than This Number Of Records Read, Microsoft Access doesn't display the values for that field on the list. Consequently, you need to change the setting for this option. Because Microsoft Access reads all values in nonindexed fields, not just unique values, set this option to a number greater than (or equal to) the number of records in the nonindexed field with the most values.
Note When Microsoft Access is able to display the list in a field, it only shows the unique values, even for a nonindexed field.