Issue
The "Latest result" option in your lookup tables and columns brings up blank Results data, even though there is definitely non-null Results data available for that entity.
Environment
Results, lookup tables and lookup columns
Cause
The "Latest result" option looks at the most recently saved Result record only. It does not look for the most recent, non-null Result value for a specific field. Therefore, if the most recently saved Result record has a blank value in a given field, then the "Latest result" lookup value for that field will be blank, even if there are earlier non-null Results values for that field.
Resolution steps
In the short term, you can use the "All results" lookup option to get earlier Results values.
In the long term, you may have to re-configure your Results schemas to ensure that no non-null values are saved.