SYMPTOM:
In Strategy Developer 9.4.x and 10.x a Last Year transformation is not applied if defined as "One to One" and the attribute is present in the Filter definition but not in the Report objects, as shown below:

If the attribute is present in the Report objects the Last Year Transformation is applied as shown below:

CAUSE:
This is a known issue in Strategy Developer 9.4.x and 10.x.
ACTION:
Strategy will continue to investigate and post updates as soon as they are available.
WORKAROUND:
Set the Last Year transformation as "Many to Many" whilst the attribute is present in the filter definition but not in the report objects.