Maybe an obvious question but is the section access reducing correctly the rest of the data? How did you link the section access reduction field to the one in the data model? Are you using the same name, uppercase in both section access and normal script? Did you check the "Initial data reduction based on section access" in the Settings menu, Document Properties, Opening tab?
If the reduction were working fine records should be actually removed from memory, so the user should not be able to see them.
Hope that helps.