Check the protector's complete care instructions, including its backing. A washable upper layer does not establish that a waterproof membrane tolerates the selected drying treatment.
Understanding this situation
Large flat waterproof items can also have different loading behaviour from ordinary clothing. The appliance's bulky-item restrictions matter, and neither folding it smaller nor using a bag changes those limits.
A useful next step
Use a supported wash-only and separate drying route where required. Do not add extra heat to compensate for water held in folds. If the backing cracks, peels or melts, stop using the damaged item and record the care settings.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.