Bulky pieces can fold and restrict each other's movement, while their filling and size may demand different permitted treatments. A continuous programme's capacity is not a general storage-volume allowance.
Understanding this situation
A few large items can be more difficult than many small garments even at a comparable dry weight. The machine must be suitable for each item's bulk as well as its care requirements.
A useful next step
Check the bedding instructions and process only compatible amounts. Use another appropriate method where the model does not support the items. Do not force the door shut or compensate for restricted movement by choosing a longer or hotter cycle.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.