The rack is designed to hold items where wash water can reach their soiled surfaces. Positioning according to the model's guide matters more than filling every available gap.
Understanding this situation
Closely overlapping plates or a broad board across the front can shelter other items. A programme cannot compensate fully for a surface physically blocked by another object.
A useful next step
Use the recommended rack positions and leave appropriate separation. Remove large loose food remnants as directed rather than packing them between plates. If correctly arranged loads remain dirty, note the programme and location of the residue for a useful enquiry.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.