Do not guess that machine drying is safe from appearance alone. Seek the garment maker's care information or use an appropriate cautious alternative that is supported for the textile.
Understanding this situation
A missing label leaves uncertainty about fibres, finishes and trims. The washer-dryer's gentle programme does not establish universal compatibility, and a small test cycle may still cause irreversible damage.
A useful next step
Keep the item out of an automatic wash-and-dry load until its care is clear. If it has already changed, document what is known about its composition and the selected settings rather than assigning the outcome immediately to an appliance fault.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.