No programme guarantees every soil and material combination. Follow the cookware and appliance guidance for removing large remnants or appropriate preparation.
Understanding this situation
A heavily baked-on tray can require a different permitted approach from lightly soiled plates. Its size may also shield other items, making the whole load unsuitable for an ordinary quick cycle.
A useful next step
Use an appropriate programme and load arrangement without damaging the tray's finish. Do not add unsupported chemicals or put incompatible fragile items through the strongest cycle alongside it. Describe what soil remains if suitable treatment still gives a changed result.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.