Form fields not saved when reopening

I have a Dynamic XML PDF Form I created in Livecycle ES2...  Opened in Acrobat PRO and saved with Extended Features...  So users can now open the doc in Reader DC with no issues and can input data in all the form fields...  but when the file is saved, then re-opened, some fields are not saving while others are fine...  I can't see any difference in the fields that are saving versus those that aren't...  Any Ideas?