Classif.: material and assortment do not match

What causes this issue?

The check for classifying parameters shows a difference between the
material and the assortment owner.

How can this happen?

Characteristic Value - material Value - assortment owner
**********************************************************************
SIZE 12 No characteristic
COLOR Red Ditto
STYLING Fashionable <----------> Classic (difference!)

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

System Response

How to fix this error?

Error message extract from SAP system. Copyright SAP SE.