I suppose the problem is because entropy is a proxy for the number of states of an abstract configuration space which has the same observed quantity as the concrete object that you take to measure its entropy. So, for example, if you know that your object with mass M and temperature T then to measure its entropy you take all the posible states for an abstract object with mass M and temperature T and the logarithm of that number of states is the definition of the entropy of one object that has mass M and temperature T. So the more you know about the the concrete object the less number of posible states for the abstract model and so the entropy is not a property of the concrete object rather is a property of an abstract model with same fixed global properties.
