Hi , I think it depend on the entry keys of the enumeration.
Suppose you've 3 products with text field "Color" with value Red, Green, Blue.
Then you create an enumeration for the field Color in this way:
enum.Color.entry.01 = Red
enum.Color.entry.02 = Green
enum.Color.entry.03 = Blue
After you set enum Color to the field Color the system found datas that are not valid for the enum , for example Red instead of 01.
Try to set you enum in this way
so the entry key and value are the same.
Hope this help you.
Thank you so much Miriko. Your solution worked for me.